Multiple functions of l0036 in the regulation of the pathogenicity island of enterohaemorrhagic Escherichia coli O157:H7.
Diarrhoeagenic enterohaemorrhagic Escherichia coli and enteropathogenic E. coli attach to human intestinal epithelium and efface brush-border microvilli, forming an A/E (attaching and effacing) lesion. These human pathogens are phenotypically similar to the mouse pathogen Citrobacter rodentium. Genetically, they all have a homologous set of virulent genes involved in the A/E lesion, and these genes are organized on a LEE (locus of enterocyte effacement), a pathogenicity island. This island comprises 41 specific open reading frames, of which most are organized at five operons, LEE1, LEE2, LEE3, LEE4 and tir (LEE5). The expression of the LEE genes is regulated in a complicated manner, and current knowledge is that there are at least two positive regulators, Ler (LEE-encoded regulator) and GrlA (global regulator of LEE activator), and one negative regulator, called GrlR (global regulator of LEE repressor). In enterohaemorrhagic E. coli, GrlA is encoded by l0043, whereas GrlR is encoded by l0044. Here we report a fourth regulatory gene located in LEE3, namely l0036. Its expression is tightly controlled. When overexpressed, this factor, named Mpc (multiple point controller), interacts with Ler and suppresses the expression of the LEE proteins. When the translation is not initiated or terminated before maturation, the type III secretion of effectors is completely abolished. Therefore, together with the fact that several cis elements reside in the region that l0036 spans, l0036 appeared to have multiple functions in the regulation of LEE expression.
Tsai
Nien-Pei
NP
Institute of Microbiology and Immunology, National Yang-Ming University, 112 Taipei, Taiwan, Republic of China.
Wu
Yi-Chih
YC
Chen
Jenn-Wei
JW
Wu
Chih-Feng
CF
Tzeng
Chi-Meng
CM
Syu
Wan-Jr
WJ
D019453:Escherichia coli O157 / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D005816:Genetic Complementation Test; D044404:Genomic Islands / Q000235:genetics* / Q000502:physiology; D016366:Open Reading Frames; D009876:Operon / Q000235:genetics; D037521:Virulence Factors
D029968:Escherichia coli Proteins; D037521:Virulence Factors