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Infection and Immunity, July 2001, p. 4458-4464, Vol. 69, No. 7
Department of Microbiology, University of
Guelph, Guelph, Ontario N1G 2W1, Canada
Received 18 August 2000/Returned for modification 4 October
2000/Accepted 11 April 2001
A 16-kbp DNA region that contains genes involved in the
biosynthesis of the capsule of Mannheimia
(Pasteurella) haemolytica A1 has been
characterized. The gene cluster can be divided into three regions like
those of the typical group II capsule biosynthetic clusters in
gram-negative bacteria. Region 1 contains four genes (wzt, wzm, wzf, and
wza) which code for an ATP-binding cassette transport
apparatus for the secretion of the capsule materials across the
membranes. The M. haemolytica A1 wzt and
wzm genes were able to complement Escherichia
coli kpsT and kpsM mutants, respectively.
Further, the ATP binding activity of Wzt was demonstrated by its
affinity for ATP-agarose, and the lipoprotein nature of Wza was
supported by [3H]palmitate labeling. Region 2 contains
six genes; four genes (orf1/2/3/4)
code for unique functions for which no homologues have been identified
to date. The remaining two genes (nmaA and nmaB) code for homologues of
UDP-N-acetylglucosamine-2-epimerase and
UDP-N-acetylmannosamine dehydrogenase, respectively.
These two proteins are highly homologous to the E. coli
WecB and WecC proteins (formerly known as RffE and RffD), which are
involved in the biosynthesis of enterobacterial common antigen (ECA).
Complementation of an E. coli rffE/D mutant with the
M. haemolytica A1 nmaA/B genes resulted
in the restoration of ECA biosynthesis. Region 3 contains two genes
(wbrA and wbrB) which are suggested to be involved in the phospholipid modification of capsular materials.
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.7.4458-4464.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Analysis of the Capsule Biosynthetic Locus of
Mannheimia (Pasteurella)
haemolytica A1 and Proposal of a Nomenclature
System
*
Corresponding author. Mailing address: Department of
Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada. Phone: (519) 824-4120, ext. 3363. Fax: (519) 837-1802. E-mail: RLO{at}micro.uoguelph.ca.
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