A deletion in the sapA homologue cluster is responsible for the loss of the S-layer in Campylobacter fetus strain TK

Masaki Fujita, Tetsuhiro Moriya, Shuji Fujimoto, Nobuyuki Hara, Kazunobu Amako

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The surface array protein (SAP) of Campylobacter fetus strain TK is encoded by seven homologous sapA genes clustered on the chromosomal DNA. The spontaneously arising variant strain TK(SAP-) produces no SAP and carries an approximately 10-kb chromosomal deletion. To elucidate the mechanism underlying the loss of SAP synthesis, we analyzed the region containing the sapA homologues and the deletion. We constructed a physical map of the sapA cluster region by aligning the clones that contain sapA homologues. These analyses demonstrated that all sapA homologues were located within a limited region of about 50 kb of chromosomal DNA of strain TK. The TK(SAP-) deletion was located within this cluster and was 13.3 kb in size. The deletion occurred between two sapA homologues and resulted in the formation of a chimeric sapA homologue in the variant strain. Sequence analysis of the upstream regions and the conserved regions of all sapA homologues revealed a high degree of similarity. However, only one sapA homologue contained a putative promoter sequence. This promoter sequence was located in the deleted region. Thus, the deletion of the promoter appears to be responsible for the loss of SAP expression in TK(SAP-).

Original languageEnglish
Pages (from-to)196-201
Number of pages6
JournalArchives of Microbiology
Issue number4
Publication statusPublished - May 21 1997


All Science Journal Classification (ASJC) codes

  • Microbiology
  • Biochemistry
  • Molecular Biology
  • Genetics

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