Girón J A, Gómez-Duarte O G, Jarvis K G, Kaper J B
Centro de Investigaciones en Ciencias Microbiológicas, Benemérita Universidad Autónoma de Puebla, Pue, Mexico.
Gene. 1997 Jun 11;192(1):39-43. doi: 10.1016/s0378-1119(97)00039-5.
Longus is a long pilus produced by human enterotoxigenic Escherichia coli (ETEC) which shares significant structural and biochemical features with class-B type-4 pili. These pili include the toxin-coregulated pilus (TCP) of Vibrio cholerae, the bundle-forming pilus (BFP) of enteropathogenic E. coli and both longus and the colonization factor antigen III (CFA/III) of ETEC. These pili are produced under defined growth conditions indicating that they are under the control of different regulatory elements. While TCP is chromosomally encoded, the remaining pili are encoded on large virulence plasmids. Longus and CFA/III are closely related pili although certain DNA and protein differences also exist between them. This may account for the differences in the regulation, surface presentation, antigenicity, and prevalence of these two pilins among ETEC. Neighboring lngA, a second open reading frame termed lngB was found which encodes a protein with significant homology to proteins which are part of a type-II secretory system such as XcpV, OutC, and PulO of Pseudomonas aeruginosa, Erwinia chrysanthemi, and Klebsiella pneumoniae, respectively. This suggests that lngB may be an accessory gene involved in biogenesis of longus.
Longus是由产肠毒素大肠杆菌（ETEC）产生的一种长菌毛，它与B类4型菌毛具有显著的结构和生化特征。这些菌毛包括霍乱弧菌的毒素调节菌毛（TCP）、肠致病性大肠杆菌的束状菌毛（BFP）以及ETEC的Longus和定植因子抗原III（CFA/III）。这些菌毛在特定的生长条件下产生，表明它们受不同调控元件的控制。虽然TCP由染色体编码，但其余菌毛由大的毒力质粒编码。Longus和CFA/III是密切相关的菌毛，尽管它们之间也存在某些DNA和蛋白质差异。这可能解释了这两种菌毛蛋白在ETEC中的调控、表面呈现、抗原性和流行率的差异。在lngA附近，发现了第二个开放阅读框lngB，它编码的蛋白质与分别作为铜绿假单胞菌、菊欧文氏菌和肺炎克雷伯氏菌II型分泌系统一部分的蛋白质XcpV、OutC和PulO具有显著同源性。这表明lngB可能是参与Longus生物合成的一个辅助基因。
