Phase-variable bacterial loci: how bacteria gamble to maximise fitness in changing environments

作者：Zachary N. Phillips, Greg Tram, Kate L. Seib, John M. Atack · 发表于：Biochemical Society Transactions · 年份：2019 · DOI：10.1042/bst20180633 · 被引用次数：97 · 研究领域：Bacteriophages and microbial interactions、Bacterial Genetics and Biotechnology、Bacterial Infections and Vaccines

Phase-variation of genes is defined as the rapid and reversible switching of expression - either ON-OFF switching or the expression of multiple allelic variants. Switching of expression can be achieved by a number of different mechanisms. Phase-variable genes typically encode bacterial surface structures, such as adhesins, pili, and lipooligosaccharide, and provide an extra contingency strategy in small-genome pathogens that may lack the plethora of 'sense-and-respond' gene regulation systems found in other organisms. Many bacterial pathogens also encode phase-variable DNA methyltransferases that control the expression of multiple genes in systems called phasevarions (phase-variable regulons). The presence of phase-variable genes allows a population of bacteria to generate a number of phenotypic variants, some of which may be better suited to either colonising certain host niches, surviving a particular environmental condition and/or evading an immune response. The presence of phase-variable genes complicates the determination of an organism's stably expressed antigenic repertoire; many phase-variable genes are highly immunogenic, and so would be ideal vaccine candidates, but unstable expression due to phase-variation may allow vaccine escape. This review will summarise our current understanding of phase-variable genes that switch expression by a variety of mechanisms, and describe their role in disease and pathobiology.