Expression of serogroup B meningococcal capsular polysaccharide undergoes frequent phase variation involving reversible frameshift mutations within a homopolymeric repeat in the siaD gene. A high rate of phase variation is the consequence of a biochemical defect in methyl-directed mismatch repair. The mutator phenotype is associated to the absence of DNA adenine methyltransferase (Dam) activity in all pathogenic isolates and in 50% of commensal strains. Analysis of the meningococcal dam gene region revealed that in all Dam- strains a gene encoding a putative restriction endonuclease (drg) that cleaves only the methylated DNA sequence 5'-GmeATC-3' replaced the dam gene. Insertional inactivation of the dam and/or drg genes indicated that high rates of phase variation and hypermutator phenotype are caused by absence of a functional dam gene.
Hypermutation in pathogenic bacteria: frequent phase variation in meningococci is a phenotypic trait of a specialized mutator biotype / Bucci, C.; Lavitola, Alfredo; Salvatore, Paola; DEL GIUDICE, L.; Massardo, D. R.; Bruni, CARMELO BRUNO; Alifano, P.. - In: MOLECULAR CELL. - ISSN 1097-2765. - 3:4(1999), pp. 435-445. [10.1016/S1097-2765(00)80471-2]
Hypermutation in pathogenic bacteria: frequent phase variation in meningococci is a phenotypic trait of a specialized mutator biotype
LAVITOLA, ALFREDO;SALVATORE, PAOLA;BRUNI, CARMELO BRUNO;
1999
Abstract
Expression of serogroup B meningococcal capsular polysaccharide undergoes frequent phase variation involving reversible frameshift mutations within a homopolymeric repeat in the siaD gene. A high rate of phase variation is the consequence of a biochemical defect in methyl-directed mismatch repair. The mutator phenotype is associated to the absence of DNA adenine methyltransferase (Dam) activity in all pathogenic isolates and in 50% of commensal strains. Analysis of the meningococcal dam gene region revealed that in all Dam- strains a gene encoding a putative restriction endonuclease (drg) that cleaves only the methylated DNA sequence 5'-GmeATC-3' replaced the dam gene. Insertional inactivation of the dam and/or drg genes indicated that high rates of phase variation and hypermutator phenotype are caused by absence of a functional dam gene.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.