Nested DNA inversion of Campylobacter fetus S-layer genes is recA dependent

Dworkin, Joel; Shedd, Omer L.

doi:10.1128/jb.179.23.7523-7529.1997

Cited by 36 publications

(42 citation statements)

References 62 publications

(80 reference statements)

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“…In strain 23D: ACA2K101, in which the sapA and sapA2 homologs are disrupted by km and cm cassettes, respectively, the phenotypic variation can be detected by selecting colonies on kanamycinor chloramphenicol-containing media. In multiple experiments, the inversion frequency was approximately 10 Ϫ4 /CFU, confirming earlier studies (18). PCR of a dilution series of template chromosomal DNA using primer promF, paired with either primer sapAR or sapA2R, indicated that the inversion frequency in strain 23D is approximately 10 Ϫ2 /CFU ( Fig.…”

Section: Dna Inversion Occurs Despite Mutation Of the Ir And Clsssupporting

confidence: 71%

“…In the noncoding portion of the FCR, a sequence (5Ј-GCTGGTGA-3Ј) shares seven of eight bases with the Escherichia coli RecBCD recognition (Chi) site (5Ј-GCTGGTGG-3Ј), followed by three pentameric (TTTTA) repeats. Immediately following the pentameric repeats is a 15-bp inverted repeat (IR) capable of forming a stem-loop structure which ends at the ATG translation initiation codon of the sapA homologs (16,19,66).Our previous studies have shown both RecA-dependent (high-frequency) and independent (low-frequency) rearrangement of the sap invertible element (18,50). We now sought to examine the hypotheses that the FCR might contribute to inversion based on homologous recombination and that disruption of the Chi-like site (CLS) would influence the frequency of DNA inversion.…”

mentioning

confidence: 99%

“…Our previous studies have shown both RecA-dependent (high-frequency) and independent (low-frequency) rearrangement of the sap invertible element (18,50). We now sought to examine the hypotheses that the FCR might contribute to inversion based on homologous recombination and that disruption of the Chi-like site (CLS) would influence the frequency of DNA inversion.…”

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confidence: 99%

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Campylobacter fetusUses Multiple Loci for DNA Inversion within the 5′ Conserved Regions ofsapHomologs

Ray

Thompson

2001

J Bacteriol

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Campylobacter fetus cells possess multiple promoterless sap homologs, each capable of expressing a surface layer protein (SLP) by utilizing a unique promoter present on a 6.2-kb invertible element. Each sap homolog includes a 626-bp 5 conserved region (FCR) with 74 bp upstream and 552 bp within the open reading frame. After DNA inversion, the splice is seamless because the FCRs are identical. In mutant strain 23D:ACA2K101, in which sapA and sapA2 flanking the invertible element in opposite orientations were disrupted by promoterless chloramphenicol resistance (Cm r ) and kanamycin resistance (Km r ) cassettes, respectively, the frequency of DNA inversion is 100-fold lower than that of wild-type strain 23D. To define the roles of a 15-bp inverted repeat (IR) and a Chi-like site (CLS) in the FCR, we mutagenized each upstream of sapA2 in 23D:ACA2K101 by introducing NotI and KpnI sites to create strains 23D:ACA2K101N and 23D:ACA2K101K, respectively. Alternatively selecting colonies for Cm r or Km r showed that mutagenizing the IR or CLS had no apparent effect on the frequency of the DNA inversion. However, mapping the unique NotI or KpnI site in relation to the Cm r or Km r cassette in the cells that changed phenotype showed that splices occurred both upstream and downstream of the mutated sites. PCR and sequence analyses also showed that the splice could occur in the 425-bp portion of the FCR downstream of the cassettes. In total, these data indicate that C. fetus can use multiple sites within the FCR for its sap-related DNA inversion.Generation of antigenic variation is one of the mechanisms that pathogenic microorganisms have evolved to adapt to immunologically competent hosts. Such variation often reflects rearrangements of the genes encoding major antigens, which can occur by a wide variety of mechanisms (21,35,54). Such recombination may be site specific (21,29,35,54) or may involve repetitive (homologous) DNA sequences (55, 56). Most high-frequency DNA inversions involve site-specific recombination (1,21,29,35,36,71).Campylobacter fetus is a spiral gram-negative microaerophilic bacterial pathogen that interferes with reproductive function in ungulates and can cause extraintestinal infections in humans (28,32,46,59). C. fetus cells are covered by a paracrystalline surface array composed of specialized surface layer proteins (SLPs), ranging in size from approximately 97 to 149 kDa (14, 47). As shown by in vitro and in vivo studies, SLPs play a major role in C. fetus virulence (4,5,11,25,48,70). These SLPs are critical for resistance to innate host defenses by inhibiting C3b binding to the bacterial cell (6), and antigenic variation protects against antibody-mediated opsonization (28, 68).Each C. fetus cell possesses five to nine sapA homologs (19,20,26,64), clustered in a region of less than 93 kb, representing less than 8% of the bacterial chromosome (19,20). One part of the sap locus is a 6.2-kb invertible element containing the unique sapA promoter flanked by sapA homologs in opposite orientations. Variation...

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Section: Dna Inversion Occurs Despite Mutation Of the Ir And Clsssupporting

confidence: 71%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Campylobacter fetusUses Multiple Loci for DNA Inversion within the 5′ Conserved Regions ofsapHomologs

Ray

Thompson

2001

J Bacteriol

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“…Eight or nine S-layer gene cassettes are present in C. fetus wild-type cells and are tightly clustered on the genome in a region of less than 93 kb. Several studies confirmed that antigenic variation is due to the recombination of partial coding sequences (30,31). In addition to promotor inversion between two oppositely oriented gene cassettes, one of the S-layer gene cassettes bracketing the invertible element with a nonflanking, previously silent gene cassette is exchanged.…”

Section: S-layer-deficient Phenotypes and S-layer Variationmentioning

confidence: 75%

“…In addition to promotor inversion between two oppositely oriented gene cassettes, one of the S-layer gene cassettes bracketing the invertible element with a nonflanking, previously silent gene cassette is exchanged. Thus, C. fetus uses a single promoter strictly by a single DNA inversion event at frequencies independent of DNA fragment size, permitting expression of different S-layer gene cassettes (29,30). Although the S-layer protein SapB and its homologs possess an N-terminal region different from that of SapA, noncoding regions 300 bp upstream and 1,000 bp downstream of the sapA and sapB open reading frames, including promotor and transcriptional terminator sequences, were essentially identical for both types of cells (31).…”

Section: S-layer-deficient Phenotypes and S-layer Variationmentioning

confidence: 99%

S-Layer Proteins

2000

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Self‐assembling Protein Systems: Microbial S‐layers

Sleytr¹,

Sára²,

Pum³

et al. 2002

Biopolymers Online

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Introduction Historical Outline Occurrence and Ultrastructure Isolation and Chemical Characterization Molecular Biology, Genetics and Biosynthesis Assembly and Morphogenesis Self‐assembly in vivo Self‐assembly in vitro Functional Aspects Biodegradation Production of S‐layer Proteins Application of S‐layer Proteins S‐layer Ultrafiltration Membranes S‐layers as Matrix for the Immobilization of Functional Macromolecules S‐layer‐based Dipsticks Supramolecular Structures Generated by Oriented Recrystallization of S‐layer Fusion Proteins on Supports Precoated with SCWP S‐layers as Templates for the Formation of Regularly Arranged Nanoparticles S‐layers as Supporting Structures for Functional Lipid Membranes (Planar Membranes and Liposomes) S‐layers for Vaccine Development Outlook and Perspectives Patents

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Nested DNA inversion of Campylobacter fetus S-layer genes is recA dependent

Cited by 36 publications

References 62 publications

Campylobacter fetusUses Multiple Loci for DNA Inversion within the 5′ Conserved Regions ofsapHomologs

Campylobacter fetusUses Multiple Loci for DNA Inversion within the 5′ Conserved Regions ofsapHomologs

S-Layer Proteins

Self‐assembling Protein Systems: Microbial S‐layers

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