Aeromonas hydrophila AH-3 type III secretion system expression and regulatory network.
The Aeromonas hydrophila type III secretion system (T3SS) has been shown to play a crucial role in this pathogen's interactions with its host. We previously described the genetic organization of the T3SS cluster and the existence of at least one effector, called AexT, in A. hydrophila strain AH-3. In this study, we analyzed the expression of the T3SS regulon by analyzing the activity of the aopN-aopD and aexT promoters (T3SS machinery components and effector, respectively) by means of two different techniques: promoterless gfp fusions and real-time PCR. The expression of the A. hydrophila AH-3 T3SS regulon was induced in response to several environmental factors, of which calcium depletion, a high magnesium concentration, and a high growth temperature were shown to be the major ones. Once the optimal conditions were established, we tested the expression of the T3SS regulon in the background of several virulence determinant knockouts of strain AH-3. The analysis of the data obtained from axsA and aopN mutants, both of which have been described to be T3SS regulators in other species, allowed us to corroborate their function as the major transcription regulator and valve of the T3SS, respectively, in Aeromonas hydrophila. We also demonstrated the existence of a complicated interconnection between the expression of the T3SS and several other different virulence factors, such as the lipopolysaccharide, the PhoPQ two-component system, the ahyIR quorum sensing system, and the enzymatic complex pyruvate deshydrogenase. To our knowledge, this is the first study of the A. hydrophila T3SS regulatory network.
Vilches
Silvia
S
Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, 08071 Barcelona, Spain.
Jimenez
Natalia
N
Tomás
Juan M
JM
Merino
Susana
S
D016980:Aeromonas hydrophila / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019677:Artificial Gene Fusion; D002118:Calcium / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects* / Q000528:radiation effects*; D055786:Gene Knockout Techniques; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D008274:Magnesium / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000096:biosynthesis*; D008954:Models, Biological; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D018085:Regulon; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
D026901:Membrane Transport Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D049452:Green Fluorescent Proteins; D008274:Magnesium; D002118:Calcium
Methods Mol Biol. 2000;132:365-86
10547847
J Bacteriol. 2003 Nov;185(22):6583-91
14594831
J Bacteriol. 2000 Jun;182(12):3508-16
10852884
Infect Immun. 2000 Apr;68(4):1849-54
10722573
Proteomics. 2007 Feb;7(3):436-49
17203509
Microbiol Mol Biol Rev. 1998 Jun;62(2):379-433
9618447
Appl Environ Microbiol. 2004 Nov;70(11):6914-9
15528564
J Bacteriol. 2002 Nov;184(21):5966-70
12374830
J Bacteriol. 2006 Jan;188(2):542-55
16385045
Microb Pathog. 2003 May;34(5):249-59
12732473
J Bacteriol. 2002 Jun;184(12):3214-23
12029037
J Bacteriol. 2004 Jun;186(12):3794-805
15175293
J Bacteriol. 2006 Feb;188(3):852-62
16428388
Infect Immun. 2004 Mar;72(3):1248-56
14977925
Annu Rev Microbiol. 2000;54:735-74
11018143
J Bacteriol. 2006 Oct;188(19):6889-98
16980492
ISME J. 2008 Aug;2(8):843-52
18480848
Mol Microbiol. 2006 Nov;62(3):631-40
16995895
Microbiology (Reading). 2004 Apr;150(Pt 4):843-851
15073294
Science. 1999 May 21;284(5418):1322-8
10334981
Microbiology (Reading). 2006 Jun;152(Pt 6):1847-1856
16735747
Mol Microbiol. 2004 Apr;52(2):451-69
15066033
FEMS Microbiol Lett. 2006 Oct;263(2):127-35
16978346
Infect Immun. 2002 Jul;70(7):3973-7
12065547
J Bacteriol. 2005 Jun;187(11):3898-902
15901720
Microb Pathog. 2008 Jan;44(1):1-12
17689917
Mol Microbiol. 1995 Nov;18(3):533-46
8748036
Proc Natl Acad Sci U S A. 2003 Mar 18;100(6):3027-30
12631703
J Bacteriol. 2004 Jul;186(14):4694-704
15231802
Clin Infect Dis. 1998 Aug;27(2):332-44
9709884
J Bacteriol. 2002 Apr;184(7):1851-8
11889090
Science. 2005 Feb 25;307(5713):1313-7
15731456
J Mol Biol. 1983 Jun 5;166(4):557-80
6345791
J Bacteriol. 2007 Mar;189(6):2203-9
17209027
Microbiology (Reading). 2006 May;152(Pt 5):1275-1286
16622045
Curr Opin Microbiol. 2002 Apr;5(2):166-72
11934613
Proc Natl Acad Sci U S A. 1999 Dec 21;96(26):15196-201
10611361
Mol Microbiol. 2005 Aug;57(4):970-87
16091038
J Bacteriol. 1996 Mar;178(5):1310-9
8631707
J Bacteriol. 2000 Jun;182(12):3498-507
10852883
Microb Pathog. 2007 Oct;43(4):127-46
17644303
J Bacteriol. 1997 Dec;179(23):7581-6
9393727
Microbiology (Reading). 2006 Sep;152(Pt 9):2809-2818
16946275
J Bacteriol. 2007 Apr;189(8):3124-32
17307856
J Bacteriol. 2008 Jun;190(12):4198-209
18408022