Wang L, Jensen S, Hallman R, Reeves P R
Department of Microbiology, University of Sydney, Australia.
FEMS Microbiol Lett. 1998 Aug 1;165(1):201-6. doi: 10.1111/j.1574-6968.1998.tb13147.x.
O antigen genes are clustered, with a JUMPstart sequence located upstream. JUMPstart is a 39-bp sequence, present upstream of many polysaccharide gene clusters and also upstream of haemolysin and F factor gene clusters. RfaH is known to regulate the expression of E. coli group II capsule, haemolysin, F factor and the outer core of lipopolysaccharide all of which have the JUMPstart sequence, and has been shown to function as a transcriptional antiterminator in some cases. Using lacZ fusions to genes in the O antigen gene cluster of Salmonella enterica serovar Typhimurium, we found that RfaH also regulates the expression of O antigen. We showed that RfaH enhances expression of the 18-kb O antigen gene cluster, with promoter-distal genes affected more dramatically. We also showed that the JUMPstart sequence was required for RfaH function.
O抗原基因成簇排列，其上游有一个JUMPstart序列。JUMPstart是一个39个碱基对的序列，存在于许多多糖基因簇的上游，也存在于溶血素和F因子基因簇的上游。已知RfaH可调节大肠杆菌II型荚膜、溶血素、F因子和脂多糖外核心的表达，所有这些都具有JUMPstart序列，并且在某些情况下已显示其作为转录抗终止子发挥作用。利用与鼠伤寒沙门氏菌O抗原基因簇中的基因的lacZ融合，我们发现RfaH也调节O抗原的表达。我们表明，RfaH增强了18kb O抗原基因簇的表达，启动子远端的基因受到的影响更为显著。我们还表明，JUMPstart序列是RfaH发挥功能所必需的。
