Burrows L L, Chow D, Lam J S
Department of Microbiology, University of Guelph, Ontario, Canada.
J Bacteriol. 1997 Mar;179(5):1482-9. doi: 10.1128/jb.179.5.1482-1489.1997.
The wbp gene cluster, encoding the B-band lipopolysaccharide O antigen of Pseudomonas aeruginosa serotype O5 strain PAO1, was previously shown to contain a wzy (rfc) gene encoding the O-antigen polymerase. This study describes the molecular characterization of the corresponding wzz (rol) gene, responsible for modulating O-antigen chain length. P. aeruginosa O5 Wzz has 19 to 20% amino acid identity with Wzz of Escherichia coli, Salmonella enterica, and Shigella flexneri. Knockout mutations of the wzz gene in serotypes O5 and O16 (which has an O antigen structurally related to that of O5) yielded mutants expressing O antigens with a distribution of chain lengths differing markedly from that of the parent strains. Unlike enteric wzz mutants, the P. aeruginosa wzz mutants continued to display some chain length modulation. The P. aeruginosa O5 wzz gene complemented both O5 and O16 wzz mutants as well as an E. coli wzz mutant. Coexpression of E. coli and P. aeruginosa wzz genes in a rough strain of E. coli carrying the P. aeruginosa wbp cluster resulted in the expression of two populations of O-antigen chain lengths. Sequence analysis of the region upstream of wzz led to identification of the genes rpsA and himD, encoding 30S ribosomal subunit protein S1 and integration host factor, respectively. This finding places rpsA and himD adjacent to wzz and the wbp cluster at 37 min on the PAO1 chromosomal map and completes the delineation of the O5 serogroup-specific region of the wbp cluster.
wbp基因簇编码铜绿假单胞菌O5血清型菌株PAO1的B带脂多糖O抗原，此前已证明该基因簇包含一个编码O抗原聚合酶的wzy（rfc）基因。本研究描述了负责调节O抗原链长度的相应wzz（rol）基因的分子特征。铜绿假单胞菌O5 Wzz与大肠杆菌、肠炎沙门氏菌和福氏志贺氏菌的Wzz具有19%至20%的氨基酸同一性。O5和O16血清型（其O抗原在结构上与O5相关）中wzz基因的敲除突变产生了表达O抗原的突变体，其链长分布与亲本菌株明显不同。与肠道wzz突变体不同，铜绿假单胞菌wzz突变体继续表现出一些链长调节。铜绿假单胞菌O５ wzz基因对O5和O16 wzz突变体以及大肠杆菌wzz突变体均有互补作用。在携带铜绿假单胞菌wbp基因簇的大肠杆菌粗糙菌株中共表达大肠杆菌和铜绿假单胞菌的wzz基因，导致表达出两种O抗原链长群体。对wzz上游区域的序列分析导致鉴定出rpsA和himD基因，它们分别编码30S核糖体亚基蛋白S1和整合宿主因子。这一发现将rpsA和himD定位在PAO1染色体图谱上37分钟处wzz和wbp基因簇的旁边，并完成了wbp基因簇O5血清群特异性区域的描绘。
