HosA, a member of the SlyA family, regulates motility in enteropathogenic Escherichia coli.
In enteropathogenic and enterohemorraghic Escherichia coli (EPEC and EHEC), two members of the SlyA family of transcriptional regulators have been identified as SlyA. Western blot analysis of the wild type and the corresponding hosA and slyA deletion mutants indicated that SlyA and HosA are distinct proteins whose expression is not interdependent. Of 27 different E. coli strains (EPEC, EHEC, enteroinvasive, enteroaggregative, uropathogenic, and commensal) examined, 14 were positive for both genes and proteins. To investigate hosA expression, a hosA::luxCDABE reporter gene fusion was constructed. hosA expression was significantly reduced in the hosA but not the slyA mutant and was influenced by temperature, salt, and pH. In contrast to SlyA, HosA did not activate the cryptic E. coli K-12 hemolysin ClyA. Mutation of hosA did not influence type III secretion, the regulation of the LEE1 and LEE4 operons, or the ability of E2348/69 to form attaching-and-effacing lesions on intestinal epithelial cells. HosA is, however, involved in the temperature-dependent positive control of motility on swim plates and regulates fliC expression and FliC protein levels. In electrophoretic mobility shift assays, purified HosA protein bound specifically to the fliC promoter, indicating that HosA directly modulates flagellin expression. While direct examination of flagellar structure and the motile behavior of individual hosA cells grown in broth culture at 30 degrees C did not reveal any obvious differences, hosA mutants, unlike the wild type, clumped together, forming nonmotile aggregates which could account for the markedly reduced motility of the hosA mutant on swim plates at 30 degrees C. We conclude that SlyA and HosA are independent transcriptional regulators that respond to different physicochemical cues to facilitate the environmental adaptation of E. coli.
Ferrándiz
Maria-José
MJ
Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand. h.withers@auckland.ac.nz.
Bishop
Keith
K
Williams
Paul
P
Withers
Helen
H
D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007422:Intestines / Q000382:microbiology; D008969:Molecular Sequence Data; D009068:Movement; D009154:Mutation; D017422:Sequence Analysis, DNA; D013696:Temperature; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C498398:HosA protein, E coli; D014157:Transcription Factors; C056785:salmolysin
Mol Microbiol. 2000 Feb;35(3):677-85
10672189
Infect Immun. 1999 Oct;67(10):5192-9
10496895
J Clin Invest. 2001 Mar;107(5):539-48
11238553
Nat Struct Biol. 2001 Aug;8(8):710-4
11473263
Mol Microbiol. 2001 Sep;41(6):1249-69
11580832
Mol Microbiol. 2002 Apr;44(2):361-79
11972776
J Biol Chem. 2002 May 17;277(20):17630-7
11882648
J Bacteriol. 2002 Jul;184(13):3549-59
12057949
Infect Immun. 2002 Jul;70(7):3500-9
12065489
Trends Microbiol. 2002 Jun;10(6):267-8
12088660
J Biol Chem. 2003 May 30;278(22):20240-4
12649270
J Mol Biol. 1983 Jun 5;166(4):557-80
6345791
J Infect Dis. 1985 Sep;152(3):550-9
2863318
Gene. 1989 Apr 15;77(1):51-9
2744487
Gene. 1989 Aug 1;80(1):161-9
2551782
Proc Natl Acad Sci U S A. 1994 Jan 18;91(2):489-93
8290552
Mol Microbiol. 1994 Mar;11(6):1127-39
8022282
Mol Microbiol. 1993 Nov;10(3):511-20
7968529
J Bacteriol. 1995 Jul;177(14):4121-30
7608087
Mol Gen Genet. 1995 Dec 15;249(5):474-86
8544813
J Bacteriol. 1996 Mar;178(5):1310-9
8631707
Mol Microbiol. 1996 Apr;20(1):191-9
8861216
Mol Microbiol. 1996 Aug;21(3):441-8
8866468
Infect Immun. 1997 Jul;65(7):2606-12
9199427
Mol Microbiol. 1997 Nov;26(3):531-44
9402023
Clin Microbiol Rev. 1998 Jan;11(1):142-201
9457432
FEMS Microbiol Lett. 1998 Jun 15;163(2):193-202
9673022
J Bacteriol. 1999 Jul;181(13):4114-7
10383984
Mol Microbiol. 1999 Jul;33(2):296-306
10411746
J Bacteriol. 2000 Oct;182(19):5381-90
10986240