Affiliation:
1. Department of Dairy and Food Science, Centre of Advanced Food Studies, The Royal Veterinary and Agricultural University, DK-1958 Frederiksberg C, Denmark
Abstract
ABSTRACT
The type II restriction-modification (R-M) system LlaDII isolated from
Lactococcus lactis
contains two tandemly arranged genes,
llaDIIR
and
llaDIIM
, encoding a restriction endonuclease (REase) and a methyltransferase (MTase), respectively. Interestingly, two LlaDII recognition sites are present in the
llaDIIM
promoter region, suggesting that they may influence the activity of the promoter through methylation status. In this study, separate promoters for
llaDIIR
and
llaDIIM
were identified, and the regulation of the two genes at the transcriptional level was investigated. DNA fragments containing the putative promoters were cloned in a promoter probe vector and tested for activity in the presence and absence of the active MTase. The level of expression of the MTase was 5- to 10-fold higher than the level of expression of the REase. The results also showed that the presence of M.LlaDII reduced the in vivo expression of the
llaDIIM
promoter (P
llaDIIM
) up to 1,000-fold, whereas the activity of the
llaDIIR
promoter (P
llaDIIR
) was not affected. Based on site-specific mutations it was shown that both of the LlaDII recognition sites within P
llaDIIM
are required to obtain complete repression of transcriptional activity. No regulation was found for
llaDIIR
, which appears to be constitutively expressed.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
19 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献