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Cloning and genetic analysis of serotype 5 M protein determinant of group A streptococci: evidence for multiple copies of the M5 determinant in the Streptococcus pyogenes genome.

Abstract：

:A gene bank of group A Streptococcus strain Manfredo (M protein serotype 5) was constructed with a bacteriophage lambda vector-Escherichia coli K-12 host system and screened by immunoblotting hybrid phage plaques with antisera raised to purified pep M5 (serotype 5 M protein fragment released from the streptococcal cell surface by pepsin). Hybrid phage expressing M5 antigen (lambda M5) were detected in the gene bank at an unexpectedly high frequency. The cloned streptococcal DNA sequences from one lambda M5 phage were subcloned into an E. coli plasmid vector. The M5 gene (smp5) was mapped, and its transcriptional orientation was determined by isolating and characterizing deletion and transposon insertion mutants of the M5+ hybrid plasmid pMK207. This analysis indicated that the intact smp5 gene had been cloned. Anti-pep M5 sera reacted with five pMK207-encoded polypeptides having relative molecular sizes of 64,000, 56,000, 55,500, 52,500, and 50,000. All of these polypeptides were encoded by the same DNA sequences, and all reacted with antisera raised to a synthetic peptide corresponding to the amino-terminal end of pep M5, suggesting that proteolytic cleavage at the carboxy-terminal end of the smp5 gene product generates at least some of the lower relative molecular size forms. Southern blotting experiments with smp5 gene sequences as probes identified multiple copies of DNA sequences sharing homology with the smp5 gene in the type 5 group A streptococcal genome.

journal_name

Infect Immun

journal_title

Infection and immunity

authors

Kehoe MA,Poirier TP,Beachey EH,Timmis KN

doi

10.1128/IAI.48.1.190-197.1985

subject

Has Abstract

pub_date

1985-04-01 00:00:00

pages

190-7

issue

1

eissn

0019-9567

issn

1098-5522

journal_volume

48

pub_type

杂志文章

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