Previous Article | Next Article 
Antimicrobial Agents and Chemotherapy, July 2005, p. 3004-3008, Vol. 49, No. 7
0066-4804/05/$08.00+0 doi:10.1128/AAC.49.7.3004-3008.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Production of Enterocin P, an Antilisterial Pediocin-Like Bacteriocin from Enterococcus faecium P13, in Pichia pastoris
Jorge Gutiérrez,
Raquel Criado,
María Martín,
Carmen Herranz,
Luis M. Cintas, and
Pablo E. Hernández*
Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain
Received 24 November 2004/
Returned for modification 14 January 2004/
Accepted 25 February 2005

ABSTRACT
The gene encoding mature enterocin P (EntP), an antimicrobial
peptide from
Enterococcus faecium P13, was cloned into the pPICZ

A
expression vector to generate plasmid pJC31. This plasmid was
integrated into the genome of
P. pastoris X-33, and EntP was
heterologously secreted from the recombinant
P. pastoris X-33t
1 derivative at a higher production and antagonistic activity
than from
E. faecium P13.

TEXT
Compounds with antimicrobial activity are produced by a wide
range of mammals, birds, insects, plants, and microorganisms,
while ribosomally synthesized antimicrobial peptides produced
by bacteria are generally referred to as bacteriocins (
14,
29).
Bacteriocin production is common in lactic acid bacteria (LAB),
and since bacteriocins produced by LAB may inhibit gram-positive
spoilage bacteria and food-borne pathogens (
9,
31), they are
attracting considerable interest for their potential use as
natural and nontoxic food preservatives (
10,
30). Enterocin
P (EntP) is a class IIa bacteriocin produced by
Enterococcus faecium P13 (
7). The EntP structural gene (
entP) encodes a 71-amino-acid
prepeptide consisting of a 44-amino-acid mature bacteriocin
and a 27-amino-acid signal peptide. The mature EntP is a bacteriocin
with a broad antimicrobial spectrum that inhibits food-borne
pathogens such as
Listeria monocytogenes,
Clostridium perfringens,
Clostridium botulinum, and
Staphylococcus aureus (
7), while
the
entP gene seems to be widely distributed in
E. faecium strains
of different origins (
8,
12,
21). EntP has also been shown to
dissipate the membrane potential of energized cells and to form
specific potassium ion-conducting pores in the cytoplasmic membranes
of target cells (
19,
20). The broad antimicrobial spectrum of
EntP suggests its potential application as a natural antimicrobial
additive in the food industry. However, the use of enterococci
as producers of bacteriocins should be approached with caution,
since many
Enterococcus isolates code for potential virulence
factors and carry antibiotic resistance genes (
13,
15,
16).
For biotechnological, hygienic, and safety reasons, the cloning,
production, and functional expression of bacteriocins produced
by enterococci in heterologous hosts should be evaluated. The
yeast
Pichia pastoris has proven valuable for the heterologous
production of peptides and proteins due to its ability to produce
foreign proteins at high levels (
6,
17). Thus, we report in
this communication the cloning, production, and functional expression
of EntP by
P. pastoris.
Bacterial strains, plasmids, growth conditions, and basic genetic techniques.
E. faecium P13 (7) and E. faecium T136 (4) were grown in MRS broth (Oxoid). The pCR2.1-TOPO vector, Escherichia coli TOP-10 and E. coli MAX Efficiency DH5
competent cells, the pPICZ
A expression vector, and the Pichia pastoris X-33 host were from Invitrogen. The E. coli cells were propagated in Luria-Bertani (LB) broth (Sigma). The P. pastoris X-33t1 clone was grown in buffered methanol minimal (BMM) medium (1.34% yeast nitrogen base, 4 x 105% biotin, 100 mM potassium phosphate [pH 6], 0.5% methanol) and BMMY (BMM with 1% yeast extract and 2% peptone) to induce production of EntP. Total genomic DNA was isolated using the Wizard DNA purification kit (Promega). All DNA-modifying enzymes were from New England Biolabs, and Platinum Taq DNA polymerase was from Invitrogen. The PCR-generated fragments were extracted from agarose gels using the Real Clean Matrix kit (C. E. Durviz, Madrid, Spain) and purified by the QIAquick PCR purification kit (QIAGEN). Competent P. pastoris X-33 cells were obtained as recommended (Invitrogen).
Construction of the recombinant plasmid pJC31.
Primers JC1 (5'-AATTATACTCGAGAAAAGAGCTACGCGTTCATATGGTAATGGTG-3') and JC2 (5'-ATTAGTTTCTAGAATATTAATGTCCCATACCTGCCAAACCAG-3') were used for PCR amplification from total genomic DNA of E. faecium P13 of a 170-bp XhoI-XbaI fragment (insert JC) carrying the
-factor kex2 signal cleavage fused to the mature EntP (entP) nucleotide sequence. Cloning of fragment JC in plasmid pCR2.1-TOPO and transformation of E. coli TOP-10 cells permitted selection of a clone containing plasmid pJC14. Plasmid pJC14 was digested with XhoI and XbaI, and the resulting 154-bp cleaved fragment was ligated into plasmid pPICZ
A, to give plasmid pJC31. Competent E. coli DH5
cells were transformed with pJC31 and the resulting transformants confirmed by PCR amplification and sequencing. Purified pJC31 was linearized with SacI and used to transform competent P. pastoris X-33 cells, in which the presence of the integrated pJC31 genes was confirmed by a bacteriocinogenicity test, PCR, and DNA sequencing of the inserts.
Heterologous production and functional expression of EntP by P. pastoris.
Heterologous expression systems for production and secretion of cloned bacteriocins have already been developed in bacteria, mostly in LAB hosts using dedicated ABC transport signals (1, 2, 23, 24, 28) or the Sec pathway (2, 25-27). However, yeasts have not yet been fully exploited as alternative heterologous hosts for production of bacteriocins. Although several yeast species are being used as heterologous production systems, Saccharomyces cerevisiae has not always proven to be ideal as a foreign gene expression host, including the heterologous production of bacteriocins (34, 35). In this work we have produced EntP, a pediocin-like bacteriocin, by using the methylotrophic yeast P. pastoris. Plasmid pPICZ
A was selected as the expression vector because it contains the S. cerevisae alpha mating factor (
-MF prepro) leader sequence (11) to target fused proteins to the secretory pathway, a methanol-inducible promoter, and the AOX1 region, which allows integration of the vector into the P. pastoris genome. The gene encoding mature EntP was cloned into pPICZ
A in frame to the
-factor secretion signal peptide without the Glu-Ala spacers adjacent to the Kex2 protease cleavage site (3). When the recombinant vector pJC31 was linearized and transformed into P. pastoris X-33 competent cells, the P. pastoris X-33t1 derivative showed a potent direct antimicrobial activity (Fig. 1).
The heterologous production of EntP by
P. pastoris X-33t
1 was
further evaluated and quantified by an agar well diffusion test
and a microtiter plate assay (MPA) performed as previously described
(
8), and by specific anti-EntP antibodies in a noncompetitive
indirect enzyme-linked immunosorbent assay (
18). Results from
Fig.
2 indicate that supernatants of
P. pastoris X-33t
1 grown
in the minimal medium BMM produced smaller halos of inhibition
(Fig.
2A) than supernatants of the same culture grown in the
complex medium BMMY (Fig.
2B). Moreover, the halos generated
by the supernatant of the culture grown in BMMY were larger,
and its activity lasted longer during the fermentation period,
than those of the culture grown in BMM. Table
1 also indicates
that maximum production of EntP during the growth of
P. pastoris X-33t
1 in BMM (22.8 µg/ml) represents a threefold increase
over production by
E. faecium P13 (7.5 µg/ml), but its
antimicrobial activity (163 bacteriocin units [BU]/ml) was only
26% of that of the EntP produced by
E. faecium P13 (625 BU/ml).
However, maximum production of EntP by
P. pastoris X-33t
1 grown
in BMMY (28.2 µg/ml) was 3.7-fold higher, and its antimicrobial
activity (10,240 BU/ml) 16-fold higher, than production and
activity of EntP by
E. faecium P13. The specific antimicrobial
activity of EntP from the supernatant of
P. pastoris X-33t
1 grown in BMMY (363 BU/µg) was also higher than that of
EntP in the supernatant of
E. faecium P13 (83 BU/µg).
Salts and other components of the BMM medium may be responsible
for the low antimicrobial activity of EntP in the presence of
reasonable amounts of the bacteriocin (Table
1). Salt inhibition
has previously been reported to reduce the inhibitory activity
of antimicrobial peptides, including nisin (
37). However, neutral
proteases (
34) might also be responsible for the observed reduced
antigen epitope recognition, leading to a decrease in the EntP
production and activity of the supernatants of
P. pastoris X-33t
1 grown in BMMY (Table
1).
View this table:
[in this window]
[in a new window]
|
TABLE 1. Production and antimicrobial activities of enterocin P from supernatants of P. pastoris X-33t1 grown in different mediaa
|
Purification of EntP, Western blotting, and mass spectrometry analysis.
Purification of EntP from the supernatants of
E. faecium P13
and
P. pastoris X-33t
1 generated two chromatographic peaks with
antagonistic activity (Table
2). The existence of multiple chromatographic
peaks after purification of EntP has been reported previously
(
18,
21) and is ascribed to the coexistence after reversed-phase
fast protein liquid chromatography (RP-FPLC) of oxidized and
nonoxidized forms of the bacteriocin. However, the yield of
EntP from the
P. pastoris X-33t
1 culture was lower than that
from
E. faecium P13. Reduced adsorption/desorption of EntP to
the cation-exchange, hydrophobic-interaction, and RP-FPLC supports
are rate-limiting steps for purification of larger quantities
of this bacteriocin from
P. pastoris. Thus, the overproduction
of EntP from recombinant yeast strains would not be useful without
the development and optimization of more-efficient purification
procedures for this bacteriocin. Further characterization of
EntP in fractions B from
E. faecium P13 and
P. pastoris X33t
1 was performed by protein electrophoresis, Western blotting,
and an overlay assay, as previously described (
18). The results
shown in Fig.
3 suggest that EntP produced by
P. pastoris X-33t
1 has a strong tendency to form aggregates with antimicrobial
activity. After matrix-assisted laser desorption ionization-time-of-flight
(MALDI-TOF) mass spectrometry analysis in a Voyager-DE STR Instrument
(PerSeptive Biosystems), both purified EntP from
E. faecium P13 and that from
P. pastoris X-33t
1 gave a major fragment of
identical molecular mass (results not shown), suggesting that
the pJC31 vector directs the processing and secretion of EntP
adequately in
P. pastoris X-33t
1.
From the results of this work, it is clear that the heterologous
production and functional expression of EntP in
P. pastoris have become successful and readily quantifiable events. The
heterologous production of proteins and peptides in yeasts permits
posttranslational events such as proteolytic maturation, glycosylation,
and disulfide bond formation. Although the amino acid sequence
of EntP contains a potential glycosylation site (Asn-Asn-Ser),
the fact that the purified EntP proteins from
E. faecium P13
and
P. pastoris X-33t
1 show identical molecular masses suggests
that the EntP glycosylation site was not recognized. Pediocin
PA-1 (
32) and plantaricin 423 (
35) have been produced by recombinant
S. cerevisiae hosts, but no inhibitory activity was detected
in the supernatants of the recombinant yeasts without concentration;
it is speculated that the bacteriocins remained cell wall associated.
Moreover, EntP is the first fully active bacteriocin produced
by
P. pastoris. The large production and high antimicrobial
activity of the EntP in the supernatants of
P. pastoris X-33t
1 may facilitate future applications of this bacteriocin in the
food industry. Many pharmaceuticals and enzymes derived from
methylotrophic yeasts either have entered the market or are
expected to do so in the near future (
17,
22). Further strategies
for optimal production of EntP by
P. pastoris may include the
use of protease-deficient host strains and unbuffered media
to inactivate neutral proteases (
34), production in fermentors
(
5), an increase in the cellular mass by using carbon sources
that support growth and do not repress methanol induction (
33),
and the use of appropriate flask designs (
36).

ACKNOWLEDGMENTS
This work was partially supported by grant 07G/0026/2000 from
the Comunidad de Madrid and grants AGL2000-0706 and AGL2003-01508
from the Ministerio de Educación y Cultura, Spain. J.G.
is the recipient of a fellowship from the Ministerio de Ciencia
y Tecnología (MCYT), and R.C. and M.M. hold fellowships
from the Ministerio de Educación, Cultura y Deporte (MECD),
Spain.

FOOTNOTES
* Corresponding author. Mailing address: Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain. Phone: 34-913943752. Fax: 34-913943743. E-mail:
ehernan{at}vet.ucm.es.


REFERENCES
1 - Axelsson, L., T. Katla, M. Bjornslett, V. G. H. Eijsink, and A. Holck. 1998. A system for heterologous expression of bacteriocins in Lactobacillus sake. FEMS Microbiol. Lett. 168:137-143.[CrossRef][Medline]
2 - Biet, F., J. M. Berjeaud, R. W. Worobo, Y. Cenatempo, and C. Fremaux. 1998. Heterologous expression of the bacteriocin mesentericin Y105 using the dedicated transport system and the general secretion pathway. Microbiology 144:2845-2854.[Abstract/Free Full Text]
3 - Brake, A. J., J. P. Merryweather, D. G. Coit, U. A. Heberlein, F. R. Masiarz, G. T. Mullenbach, M. S. Urdea, P. Valenzuela, and P. J. Barr. 1984.
-Factor-directed synthesis and secretion of mature foreign proteins in Saccharomyces cerevisiae. Proc. Natl. Acad. Sci. USA 81:4642-4646.[Abstract/Free Full Text]
4 - Casaus, P., T. Nilsen, L. M. Cintas, I. F. Nes, P. E. Hernández, and H. Holo. 2000. Enterocin B, a new bacteriocin from Enterococcus faecium T136 which can act synergistically with enterocin A. Microbiology 143:2287-2294.
5 - Cereghino, G. P. L., J. L. Cereghino, C. Ilgen, and J. M. Cregg. 2002. Production of recombinant proteins in fermenter cultures of the yeast Pichia pastoris. Curr. Opin. Biotechnol. 13:329-332.[CrossRef][Medline]
6 - Cereghino, J. L., and J. M. Cregg. 2000. Heterologous protein expression in the methylotrophic yeast Pichia pastoris. FEMS Microbiol. Rev. 24:45-66.[CrossRef][Medline]
7 - Cintas, L. M., P. Casaus, L. S. Håvarstein, P. E. Hernández, and I. F. Nes. 1997. Biochemical and genetic characterization of enterocin P, a novel sec-dependent bacteriocin from Enterococcus faecium P13 with a broad antimicrobial spectrum. Appl. Environ. Microbiol. 63:4321-4330.[Abstract]
8 - Cintas, L. M., P. Casaus, C. Herranz, L. S. Håvarstein, H. Holo, P. E. Hernández, and I. F. Nes. 2000. Biochemical and genetic evidence that Enterococcus faecium L50 produces enterocins L50A and L50B, the sec-dependent enterocin P, and a novel bacteriocin secreted without an N-terminal extension termed enterocin Q. J. Bacteriol. 182:6806-6814.[Abstract/Free Full Text]
9 - Cintas, L. M., P. Casaus, C. Herranz, I. F. Nes, and P. E. Hernández. 2001. Bacteriocins of lactic acid bacteria. Food Sci. Technol. Int. 7:281-305.[CrossRef]
10 - Cleveland, J., T. J. Montville, I. F. Nes, and M. L. Chikindas. 2001. Bacteriocins: safe, natural antimicrobials for food preservation. Int. J. Food Microbiol. 71:1-20.[CrossRef][Medline]
11 - Cregg, J. M., T. S. Vedvick, and W. C. Raschke. 1993. Recent advances in the expression of foreign genes in Pichia pastoris. Bio/Technology 11:905-910.[CrossRef][Medline]
12 - de Vuyst, L., M. R. Foulquie Moreno, and H. Revets. 2003. Screening for enterocins and detection of hemolysin and vancomycin resistance in enterococci of different origins. Int. J. Food Microbiol. 84:299-318.[CrossRef][Medline]
13 - Eaton, T. J., and M. J. Gasson. 2001. Molecular screening of Enterococcus virulence determinants and potential for genetic exchange between food and medical isolates. Appl. Environ. Microbiol. 67:1628-1635.[Abstract/Free Full Text]
14 - Eijsink, V. G. H., L. Axelsson, D. B. Diep, L. S. Håvarstein, H. Holo, and I. F. Nes. 2002. Production of class II bacteriocins by lactic acid bacteria; an example of biological warfare and communication. Antonie Leeuwenhoek 81:639-654.
15 - Franz, C. M. A. P., W. H. Holzapfel, and M. E. Stiles. 1999. Enterococci at the crossroads of food safety? Int. J. Food Microbiol. 47:1-24.[CrossRef][Medline]
16 - Franz, C. M. A. P., A. B. Muscholl-Silberhorn, N. M. K. Yousif, M. Vancanneyt, J. Swings, and W. H. Holzapfel. 2001. Incidence of virulence factors and antibiotic resistance among enterococci isolated from food. Appl. Environ. Microbiol. 67:4385-4389.[Abstract/Free Full Text]
17 - Gellisen, G. 2000. Heterologous protein production in methylotrophic yeasts. Appl. Microbiol. Biotechnol. 54:741-750.[CrossRef][Medline]
18 - Gutiérrez, J., R. Criado, R. Citti, M. Martín, C. Herranz, M. F. Fernández, L. M. Cintas, and P. E. Hernández. 2004. Performance and applications of polyclonal anti-peptide antibodies specific for the enterococcal bacteriocin enterocin P. J. Agric. Food Chem. 52:2247-2255.
19 - Herranz, C., Y. Chen, L. M. Cintas, P. E. Hernández, T. J. Montville, and M. L. Chikindas. 2001. Enterocin P selectively dissipates the membrane potential of Enterococcus faecium T136. Appl. Environ. Microbiol. 67:1689-1692.[Abstract/Free Full Text]
20 - Herranz, C., L. M. Cintas, P. E. Hernández, G. N. Moll, and A. J. M. Driessen. 2001. Enterocin P causes potassium ion efflux from Enterococcus faecium T136 cells. Antimicrob. Agents Chemother. 45:901-904.[Abstract/Free Full Text]
21 - Herranz, C., S. Mukhopadhyay, P. Casaus, J. M. Martínez, J. M. Rodríguez, I. F. Nes, L. M. Cintas, and P. E. Hernández. 1999. Biochemical and genetic evidence of enterocin P production by two Enterococcus faecium-like strains isolated from fermented sausages. Curr. Microbiol. 39:282-290.[CrossRef][Medline]
22 - Hollenberg, C. P., and G. Gellissen. 1997. Production of recombinant proteins by methylotrophic yeasts. Curr. Opin. Biotechnol. 8:554-560.[CrossRef][Medline]
23 - Horn, N., M. I. Martínez, J. M. Martínez, P. E. Hernández, M. J. Gasson, J. M. Rodríguez, and H. M. Dodd. 1999. Enhanced production of pediocin PA-1 and coproduction of nisin and pediocin PA-1 by Lactococcus lactis. Appl. Environ. Microbiol. 65:4443-4450.[Abstract/Free Full Text]
24 - Martínez, J. M., J. Kok, J. W. Sanders, and P. E. Hernández. 2000. Heterologous co-production of enterocin A and pediocin PA-1 by Lactococcus lactis: detection by specific peptide-directed antibodies. Appl. Environ. Microbiol. 66:3543-3549.[Abstract/Free Full Text]
25 - McCormick, J. K., T. R. Klaenhammer, and M. E. Stiles. 1999. Colicin V can be produced by lactic acid bacteria. Lett. Appl. Microbiol. 29:37-41.[CrossRef][Medline]
26 - McCormick, J. K., A. Poon, M. Sailer, Y. Gao, K. L. Roy, L. M. McMullen, J. C. Vederas, M. E. Stiles, and M. J. van Belkum. 1998. Genetic characterization and heterologous expression of brochocin-C, an antibotulinal, two-peptide bacteriocin produced by Brochothrix campestris ATCC 43754. Appl. Environ. Microbiol. 64:4757-4766.[Abstract/Free Full Text]
27 - McCormick, J. K., R. W. Worobo, and M. E. Stiles. 1996. Expression of the antimicrobial peptide carnobacteriocin B2 by a signal peptide-dependent general secretory pathway. Appl. Environ. Microbiol. 62:4095-4099.[Abstract]
28 - Morisset, D., and J. Frere. 2002. Heterologous expression of bacteriocins using the mesentericin Y105 dedicated transport system by Leuconostoc mesenteroides. Biochimie 84:569-576.[Medline]
29 - Nes, I. F., and H. Holo. 2000. Class II antimicrobial peptides from lactic acid bacteria. Biopolymers 55:50-61.[CrossRef][Medline]
30 - O'Sullivan, L., R. P. Ross, and C. Hill. 2002. Potential of bacteriocin-producing lactic acid bacteria for improvements in food safety and quality. Biochimie 84:593-604.[Medline]
31 - Sablon, E., B. Contreras, and E. Vandamme. 2000. Antimicrobial peptides of lactic acid bacteria: mode of action, genetics and biosynthesis. Adv. Biochem. Eng. Biotechnol. 68:21-60.[Medline]
32 - Schoeman, H., M. A. Vivier, M. du Toit, L. M. T. Dicks, and I. S. Pretorius. 1999. The development of bactericidal yeast strains by expressing the Pediococcus acidilactici pediocin gene (pedA) in Saccharomyces cerevisiae. Yeast 15:647-656.[CrossRef][Medline]
33 - Sreekrishna, K., R. G. Brankamp, K. E. Kropp, D. T. Blankenship, J. T. Tsay, P. L. Smith, J. D. Wierschke, A. Subramaniam, and L. A. Birkenberger. 1997. Strategies for optimal synthesis and secretion of heterologous proteins in the methylotrophic yeast Pichia pastoris. Gene 190:55-62.[CrossRef][Medline]
34 - Trucksis, M., T. L. Conn, A. Fasano, and J. B. Kaper. 1997. Production of Vibrio cholerae accessory cholera enterotoxin (Ace) in the yeast Pichia pastoris. Infect. Immun. 65:4984-4988.[Abstract]
35 - Van Reenen, C. A., M. L. Chikindas, W. H. van Zyl, and L. M. T. Dicks. 2002. Characterization and heterologous expression of a class IIa bacteriocin, plantaricin 423 from Lactobacillus plantarum 423, in Saccharomyces cerevisiae. Int. J. Food Microbiol. 81:29-40.
36 - Villate, F., A. S. Hussein, T. T. Bachmann, and R. D. Schmid. 2001. Expression level of heterologous proteins in Pichia pastoris is influenced by flask design. Appl. Microbiol. Biotechnol. 55:463-465.[CrossRef][Medline]
37 - Zhang, H., S. Yoshida, T. Aizawa, R. Murakami, M. Suzuki, N. Koganezawa, A. Matsuura, M. Miyazawa, K. Kawano, K. Nitta, and Y. Kato. 2000. In vitro antimicrobial properties of recombinant ASABF, an antimicrobial peptide isolated from the nematode Ascaris suum. Antimicrob. Agents Chemother. 44:2701-2705.[Abstract/Free Full Text]
Antimicrobial Agents and Chemotherapy, July 2005, p. 3004-3008, Vol. 49, No. 7
0066-4804/05/$08.00+0 doi:10.1128/AAC.49.7.3004-3008.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Sanchez, J., Borrero, J., Gomez-Sala, B., Basanta, A., Herranz, C., Cintas, L. M., Hernandez, P. E.
(2008). Cloning and Heterologous Production of Hiracin JM79, a Sec-Dependent Bacteriocin Produced by Enterococcus hirae DCH5, in Lactic Acid Bacteria and Pichia pastoris. Appl. Environ. Microbiol.
74: 2471-2479
[Abstract]
[Full Text]
-
Drider, D., Fimland, G., Hechard, Y., McMullen, L. M., Prevost, H.
(2006). The Continuing Story of Class IIa Bacteriocins. Microbiol. Mol. Biol. Rev.
70: 564-582
[Abstract]
[Full Text]