title: Comparative biology of two natural variants of the IncQ-2 family plasmids, pRAS3.1 and pRAS3.2.
abstract: Plasmids pRAS3.1 and pRAS3.2 are two closely related, natural variants of the IncQ-2 plasmid family that have identical plasmid backbones except for two differences. Plasmid pRAS3.1 has five 6-bp repeat sequences in the promoter region of the mobB gene and four 22-bp iterons in its oriV region, whereas pRAS3.2 has only four 6-bp repeats and three 22-bp iterons. Plasmid pRAS3.1 was found to have a higher copy number than pRAS3.2, and we show that the extra 6-bp repeat results in an increase in mobB and downstream mobA/repB expression. Placement of repB (primase) behind an arabinose-inducible promoter in trans resulted in an increase in repB expression and an approximately twofold increase in the copy number of plasmids with identical numbers of 22-bp iterons. The pRAS3 plasmids were shown to have a previously unrecognized toxin-antitoxin plasmid stability module within their replicons. The ability of the pRAS3 plasmids to mobilize the oriT regions of two other plasmids of the IncQ-2 family, pTF-FC2 and pTC-F14, suggested that the mobilization proteins pRAS3 are relaxed and can mobilize oriT regions with substantially different sequences. Plasmids pRAS3.1 and pRAS3.2 were highly incompatible with plasmids pTF-FC2 and pTC-F14, and this incompatibility was removed on inactivation of an open reading frame situated downstream of the mobCDE mobilization genes rather than being due to the 22-bp oriV-associated iterons. We propose that the pRAS3 plasmids represent a third, gamma incompatibility group within the IncQ-2 family plasmids.
authors.affiliation: Department of Microbiology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
authors.forename: Wesley
authors.initials: W
authors.lastname: Loftie-Eaton
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Rawlings
mesh_terms: D048409:Aeromonas salmonicida / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D014644:Genetic Variation; D010802:Phylogeny; D010957:Plasmids / Q000145:classification*
chemical_list: D001426:Bacterial Proteins
references.citation: Nucleic Acids Res. 2002 May 1;30(9):e36
references.pmid: 11972351
references.citation: J Bacteriol. 1978 Jun;134(3):1141-56
references.pmid: 149110
references.citation: J Bacteriol. 1993 Nov;175(21):6850-6
references.pmid: 8226627
references.citation: J Bacteriol. 2001 Jun;183(11):3303-9
references.pmid: 11344137
references.citation: Microbiology (Reading). 2004 Jun;150(Pt 6):1797-1808
references.pmid: 15184566
references.citation: J Bacteriol. 2005 Jul;187(14):4728-38
references.pmid: 15995187
references.citation: J Biol Chem. 1991 Aug 25;266(24):16232-7
references.pmid: 1651938
references.citation: Appl Environ Microbiol. 2000 Nov;66(11):4854-62
references.pmid: 11055935
references.citation: J Bacteriol. 1988 Apr;170(4):1461-6
references.pmid: 2832364
references.citation: J Bacteriol. 1995 Jul;177(14):4121-30
references.pmid: 7608087
references.citation: J Bacteriol. 2004 Apr;186(7):2123-33
references.pmid: 15028698
references.citation: J Bacteriol. 1974 Feb;117(2):619-30
references.pmid: 4590480
references.citation: J Bacteriol. 1985 Jan;161(1):292-8
references.pmid: 2981804
references.citation: Proc Natl Acad Sci U S A. 1985 Sep;82(18):6090-4
references.pmid: 3898079
references.citation: J Basic Microbiol. 1989;29(10):695-706
references.pmid: 2698955
references.citation: Plasmid. 2002 May;47(3):172-81
references.pmid: 12151232
references.citation: Mol Gen Genet. 1987 Jul;208(3):390-7
references.pmid: 2823058
references.citation: Nucleic Acids Res. 1999 Dec 1;27(23):4636-41
references.pmid: 10556321
references.citation: J Bacteriol. 2006 Jan;188(2):499-506
references.pmid: 16385040
references.citation: Gene. 1985;33(1):103-19
references.pmid: 2985470
references.citation: Antimicrob Agents Chemother. 2004 Oct;48(10):3989-95
references.pmid: 15388463
references.citation: Microbiol Rev. 1987 Dec;51(4):381-95
references.pmid: 3325793
references.citation: J Bacteriol. 2003 Jun;185(12):3538-46
references.pmid: 12775691
references.citation: J Bacteriol. 2003 Oct;185(20):6104-11
references.pmid: 14526022
references.citation: J Bacteriol. 1983 Jul;155(1):337-44
references.pmid: 6305917
references.citation: Mol Gen Genet. 1987 Nov;210(1):101-10
references.pmid: 3323833
references.citation: J Bacteriol. 1984 May;158(2):737-8
references.pmid: 6373729
references.citation: Biochim Biophys Acta. 1988 Dec 20;951(2-3):365-74
references.pmid: 2850014
references.citation: J Bacteriol. 1989 May;171(5):2735-9
references.pmid: 2708316
references.citation: Nucleic Acids Res. 1997 Sep 1;25(17):3389-402
references.pmid: 9254694
references.citation: Gene. 1977;2(2):95-113
references.pmid: 344137
references.citation: Mol Microbiol. 1997 Dec;26(5):961-70
references.pmid: 9426133
references.citation: J Bacteriol. 2000 Jul;182(14):4022-7
references.pmid: 10869081
references.citation: Mol Microbiol. 2000 Aug;37(3):467-76
references.pmid: 10931340
references.citation: J Biotechnol. 2006 May 29;123(3):273-80
references.pmid: 16388869
references.citation: Microbiol Mol Biol Rev. 2001 Dec;65(4):481-96, table of contents
references.pmid: 11729261
references.citation: Plasmid. 2009 Sep;62(2):98-107
references.pmid: 19481568
references.citation: J Bacteriol. 2009 Mar;191(5):1574-80
references.pmid: 19074386