1.
Characteristic and role of chromosomal type II toxin-antitoxin systems locus in Enterococcus faecalis ATCC29212.
Li, Z, Shi, C, Gao, S, Zhang, X, Lu, D, Liu, G
Journal of microbiology (Seoul, Korea). 2020;(12):1027-1036
Abstract
The Gram-positive bacterium Enterococcus faecalis is currently one of the major pathogens of nosocomial infections. The lifestyle of E. faecalis relies primarily on its remarkable capacity to face and survive in harsh environmental conditions. Toxin-antitoxin (TA) systems have been linked to the growth control of bacteria in response to adverse environments but have rarely been reported in Enterococcus. Three functional type II TA systems were identified among the 10 putative TA systems encoded by E. faecalis ATCC29212. These toxin genes have conserved domains homologous to MazF (DR75_1948) and ImmA/IrrE family metallo-endopeptidases (DR75_1673 and DR75_2160). Overexpression of toxin genes could inhibit the growth of Escherichia coli. However, the toxin DR75_1673 could not inhibit bacterial growth, and the bacteriostatic effect occurred only when it was coexpressed with the antitoxin DR75_1672. DR75_1948-DR75_1949 and DR75_160-DR75_2161 could maintain the stable inheritance of the unstable plasmid pLMO12102 in E. coli. Moreover, the transcription levels of these TAs showed significant differences when cultivated under normal conditions and with different temperatures, antibiotics, anaerobic agents and H2O2. When DR75_2161 was knocked out, the growth of the mutant strain at high temperature and oxidative stress was limited. The experimental characterization of these TAs loci might be helpful to investigate the key roles of type II TA systems in the physiology and environmental stress responses of Enterococcus.
2.
Association between XRCC1 Arg399Gln polymorphism and hepatitis virus-related hepatocellular carcinoma risk in Asian population.
Wu, D, Jiang, H, Gu, Q, Zhang, D, Li, Z
Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine. 2013;(5):3265-9
Abstract
To investigate the association between X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln polymorphism and hepatitis virus-related hepatocellular carcinoma risk, we performed a systematic meta-analysis of eligible case-control studies. Eligible studies were identified from the PubMed, Embase, and Chinese National Knowledge Infrastructure databases up to March 2013. The odds ratios (ORs) and corresponding 95 % confidence interval (95 % CI) of XRCC1 Arg399Gln polymorphism in hepatitis virus-related hepatocellular carcinoma cases compared with those in controls were calculated. The meta-analysis was performed using fixed-effect or random-effect methods according to the absence or presence of heterogeneity. This meta-analysis included 1,558 cases with hepatitis virus-related hepatocellular carcinoma and 1,338 controls. Meta-analysis of available data showed that there was no association between XRCC1 Arg399Gln polymorphism and risk of hepatitis virus-related hepatocellular carcinoma under all contrast models (Gln vs. Arg: fixed-effect OR = 0.92, 95 % CI 0.82-1.04, P = 0.18; GlnGln vs. ArgArg: random-effect OR = 0.79, 95 % CI 0.50-1.25, P = 0.32; GlnGln/ArgGln vs. ArgArg: fixed-effect OR = 0.92, 95 % CI 0.79-1.07, P = 0.28; and GlnGln vs. ArgArg/ArgGln: random-effect OR = 0.83, 95 % CI 0.52-1.34, P = 0.45). Sensitivity analysis further showed that there was no association between XRCC1 Arg399Gln polymorphism and risk of hepatitis B-related hepatocellular carcinoma under all contrast models (Gln vs. Arg: fixed-effect OR = 0.93, 95 % CI 0.82-1.05, P = 0.25; GlnGln vs. ArgArg: fixed-effect OR = 0.86, 95 % CI 0.64-1.16, P = 0.32; GlnGln/ArgGln vs. ArgArg: fixed-effect OR = 0.93, 95 % CI 0.80-1.10, P = 0.41; and GlnGln vs. ArgArg/ArgGln: fixed-effect OR = 0.85, 95 % CI 0.63-1.13, P = 0.26). Our meta-analysis of the available data did not find an obvious effect of XRCC1 Arg399Gln polymorphism on hepatitis-related hepatocellular carcinoma. More well-designed studies with large sample are needed to further verify the effect.