Biomedical subjects

Peter Pristas

Publications and source records attributed to Peter Pristas.

7 recordsLinked to original sources

PubMed2005

Multiple restriction-modification systems are present in rumen treponemes.

Type II restriction endonucleases were purified by heparin-sepharose followed by ion chromatography from Treponema strains. The results indicate that in addition to frequently cutting GATC-specific restriction enzymes, the tested strains also possess rarely cutting endonucleases. The purified restriction endonucleases represent four different sequence specificities, comprising isoschizomers of DrdI, AflII, Tth111I and NdeI. The data presented show that three rumen Treponema strains possess altogether seven type II restriction-modification systems. Thus, individual Treponema strains may be considered an interesting source of multiple type II restriction enzymes.

Animals↗

PubMed2005

Occurrence of pS86/pEF47-related plasmids in gram-positive cocci.

A small, low-copy-number cryptic 5.5-kb plasmid, designated pEF47, was isolated from a rumen bacterium Enterococcus faecalis 47 and partially characterized. Comparisons by restriction and partial sequence analysis of pEF47 demonstrated high homology to pS86 plasmid, recently isolated from a human clinical strain E. faecalis S-86. PCR followed by sequence analysis and Southern hybridization showed that pS86/pEF47-related replicons are regularly encountered in plasmids from gram-positive cocci.

Animals↗

PubMed2005

pSRD191, a new member of RepL replicating plasmid family from Selenomonas ruminantium.

A numerous plasmid population was detected in strain 19 of Selenomonas ruminantium. The population was found to consist of six plasmids in size ranging from 1.4 to more than 20kb. The smallest 1.4kb cryptic plasmid pSRD191 was further characterized. Sequence analysis identified a single ORF encoding the 177-residue putative replication protein (Rep191) which shared significant homology with RepL family of replication protein from Firmicutes (staphylococci and bacilli). PCR analysis and Southern hybridisation showed that pSRD191 related plasmids are frequently encountered in rumen selenomonads.

Amino Acid Sequence↗

PubMed2005

A unique pair of GATC specific DNA methyltransferases in Mitsuokella multiacida.

Two GATC specific methylases together with Sau3AI isoschizomeric restriction endonuclease were partially characterized in Mitsuokella multiacida 46/5. This is the first report on the presence of solitary Dam methyltransferase alongside GATC specific restriction-modification system resulting in the unusual two-fold methylation of the GATC motifs.

Bacteroidaceae↗

PubMed2005

Bacteriocin-like activity production and resistance in selected enterococci and streptococci of animal origin.

Antimicrobial proteins and peptides produced by bacteria, termed bacteriocins, are widely acknowledged to be important contributors to their producer organism survival. Enterocin A, enterocin B, enterocin P and enterolysin A belong to the best studied enterocins, i.e., bacteriocins produced by enterococci and streptococci. Twenty-one enterococcal and seven streptococcal isolates were analysed for bacteriocin-like activity production and resistance by overlay test. Up to 50% of tested strains showed antibacterial activity at least against one indicator strain. The occurrence of enterocin B structural gene in several isolates was confirmed by PCR method. The results of this study should broaden knowledge of bacteriocin-like activity production and resistance among gram-positive bacteria.

Animals↗

PubMed2005

Underrepresentation of short palindromes in Selenomonas ruminantium DNA: evidence for horizontal gene transfer of restriction and modification systems?

Molecular analysis of isolates of the rumen bacterium Selenomonas ruminantium revealed a high variety and frequency of site-specific (restriction) endonucleases. While all known S. ruminantium restriction and modification systems recognize hexanucleotide sequences only, consistently low counts of both 6-bp and 4-bp palindromes were found in DNA sequences of S. ruminantium. Statistical analysis indicated that there is some correlation between the degree of underrepresentation of tetranucleotide words and the number of known restriction endonucleases for a given sequence. Control analysis showed the same correlation in lambda DNA but not in human adenovirus DNA. Based on the data presented, it could be proposed that there is a much higher historical occurrence of restriction and modification systems in S. ruminantium and (or) frequent horizontal gene transfer of restriction and modification gene complexes.

Animals↗

PubMed2004

Different restriction and modification phenotypes in ruminal lactate-utilizing bacteria.

Analysis of restriction and modification activities in lactate-utilizing bacteria belonging to the Megasphaera elsdenii and Mitsuokella multiacida species revealed the presence of GATC-specific, MboI isospecific, restriction-modification (R-M) systems in all strains tested. While restriction endonucleases isolated from M. elsdenii strains were found to be sensitive to Dam methylation, enzymes from M. multiacida cleaved DNA irrespective of Dam methylation. The comparison of type II R-M systems specificities in three closely related lactate-utilizing ruminal bacterial species indicated complete lack of restriction and/or modification enzymes previously characterized from Selenomonas ruminantium in tested M. elsdenii and M. multiacida strains. R-M systems are believed to represent the main defense tool against phage infection. Based on the results of our experiments it could be assumed that M. elsdenii and M. multiacida use the different strategy for bacteriophage protection compared to S. ruminantium.

Animals↗