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Molecular analysis of a complex locus from Haemophilus influenzae invoked in phase‐variable lipopolysaccharide biosynthesis
Author(s) -
Maskell D. J.,
Szabo M. J.,
Butler P. D.,
Williams A. E.,
Moxon E. R.
Publication year - 1991
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1991.tb01874.x
Subject(s) - biology , haemophilus influenzae , genetics , orfs , mutant , open reading frame , gene , locus (genetics) , phase variation , reading frame , microbiology and biotechnology , peptide sequence , phenotype , bacteria
Summary A chromosomal locus, lic3 , one of several involved in lipopolysaccharide (LPS) biosynthesis by Haemophilus influenzae , was cloned and its DNA sequence determined. Iic3 comprises four closely apposed open reading frames (ORFs). ORF1 includes tandem repeats of the tetramer CAAT and two start codons out of frame with each other are found upstream of the repeats. ORF1 encodes a protein with no known homologues. 0RF2 encodes the UDP‐galactose‐4‐epimerase (galE) gene. ORF3 encodes a hydrophobic protein with no known homologues. 0RF4 encodes the adenylate kinase (adk) gene. A deletion/insertion mutation lacking the 3′ end of ORF1, all of galE , and the 5′ end of ORF3 was constructed in the parent Hib strain (RM7004). These mutants had a galE phenotype, as evidenced by galactose sensitivity, altered LPS when grown in the absence of exogenous galactose, and reduced virulence in infant rats.