Natural Transformation of Gallibacterium anatis

Kristensen, B.; Sinha, Sunita; Boyce, John D.; Bojesen, Anders Miki; Mell, Joshua Chang; Redfield, Rosemary J.

doi:10.1128/aem.00412-12

Cited by 35 publications

(23 citation statements)

References 39 publications

(44 reference statements)

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“…Other loci of importance for DNA uptake were encoded in the competence regulon, which was present in all three strains, as previously described [36]. Interestingly, F149 T exhibited a transformation frequency that was three orders of magnitude lower than 12656-12 [36].…”

Section: Resultssupporting

confidence: 70%

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Genome Analysis and Phylogenetic Relatedness of Gallibacterium anatis Strains from Poultry

et al. 2013

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Peritonitis is the major disease problem of laying hens in commercial table egg and parent stock operations. Despite its importance, the etiology and pathogenesis of this disease have not been completely clarified. Although avian pathogenic Escherichia coli (APEC) isolates have been incriminated as the causative agent of laying hen peritonitis, Gallibacterium anatis are frequently isolated from peritonitis lesions. Despite recent studies suggesting a role for G. anatis in the pathogenesis of peritonitis, little is known about the organism’s virulence mechanisms, genomic composition and population dynamics. Here, we compared the genome sequences of three G. anatis isolates in an effort to understand its virulence mechanisms and identify novel antigenic traits. A multilocus sequence typing method was also established for G. anatis and used to characterize the genotypic relatedness of 71 isolates from commercial laying hens in Iowa and 18 international reference isolates. Genomic comparisons suggest that G. anatis is a highly diverse bacterial species, with some strains possessing previously described and potential virulence factors, but with a core genome containing several antigenic candidates. Multilocus sequence typing effectively distinguished 82 sequence types and several clonal complexes of G. anatis, and some clones seemed to predominate among G. anatis populations from commercial layers in Iowa. Biofilm formation and resistance to antimicrobial agents was also observed in several clades. Overall, the genomic diversity of G. anatis suggests that multiple lineages exist with differing pathogenic potential towards birds.

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Section: Resultssupporting

confidence: 70%

“…Interestingly, F149 T exhibited a transformation frequency that was three orders of magnitude lower than 12656-12 [36]. Thus, although most G. anatis strains studied appear to be naturally competent, this ability seems differentially regulated between strains [36].…”

Section: Resultsmentioning

confidence: 91%

Genome Analysis and Phylogenetic Relatedness of Gallibacterium anatis Strains from Poultry

et al. 2013

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“…In particular, the T4P machinery is widely distributed and strongly conserved at least partly because it also provides adhesion and twitching motility (8), and, conversely, the competent species Helicobacter pylori does not use T4P to take up DNA (72,73). The taxonomic distributions of proteins that carry out homologous recombination are particularly uninformative, since these proteins have ubiquitous and conserved functions in DNA replication and repair (74).…”

Section: The Phylogenetic Distribution Of Natural Competencementioning

confidence: 99%

Natural Competence and the Evolution of DNA Uptake Specificity

2014

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Many bacteria are naturally competent, able to actively transport environmental DNA fragments across their cell envelope and into their cytoplasm. Because incoming DNA fragments can recombine with and replace homologous segments of the chromosome, competence provides cells with a potent mechanism of horizontal gene transfer as well as access to the nutrients in extracellular DNA. This review starts with an introductory overview of competence and continues with a detailed consideration of the DNA uptake specificity of competent proteobacteria in the Pasteurellaceae and Neisseriaceae. Species in these distantly related families exhibit strong preferences for genomic DNA from close relatives, a self-specificity arising from the combined effects of biases in the uptake machinery and genomic overrepresentation of the sequences this machinery prefers. Other competent species tested lack obvious uptake bias or uptake sequences, suggesting that strong convergent evolutionary forces have acted on these two families. Recent results show that uptake sequences have multiple "dialects," with clades within each family preferring distinct sequence variants and having corresponding variants enriched in their genomes. Although the genomic consensus uptake sequences are 12 and 29 to 34 bp, uptake assays have found that only central cores of 3 to 4 bp, conserved across dialects, are crucial for uptake. The other bases, which differ between dialects, make weaker individual contributions but have important cooperative interactions. Together, these results make predictions about the mechanism of DNA uptake across the outer membrane, supporting a model for the evolutionary accumulation and stability of uptake sequences and suggesting that uptake biases may be more widespread than currently thought. N aturally competent bacteria actively pull DNA fragments from their environment into their cells. These fragments provide nucleotides, but high similarity with the chromosome also allows them to change the cell's genotype by homologous recombination, a process called natural transformation ( Fig. 1; reviewed in references 1, 2, 3, 4, and 5). Most competent bacteria that have been tested can take up DNA from any source, but species in two distantly related families of Gram-negative bacteria, the Pasteurellaceae and the Neisseriaceae, show strong preferences for DNAs containing short sequences that are highly overrepresented in their own genomes, leading to preferential uptake of conspecific DNA (6). This self-specificity both raises questions about and provides a tool for investigating the evolution of competence and the mechanism of DNA uptake.We begin with a general overview of competence, emphasizing the evolutionary issues. We then describe the two components that together create self-specificity, sequence biases in the DNA uptake machinery and overrepresentation of uptake sequences in the genomes, highlighting recent work on the mechanism and evolution of uptake biases in the two families and an evolutionary model that accounts for upt...

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“…A suspension without DNA was used as the negative control. The transformation frequency was calculated as the number of transformants per CFU (29), and the transformation efficiency was calculated as the number of transformants per microgram of DNA (30).…”

Section: Methodsmentioning

confidence: 99%

Use of Natural Transformation To Establish an Easy Knockout Method in Riemerella anatipestifer

Liu

Zhang

Huang

et al. 2017

Appl Environ Microbiol

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Riemerella anatipestifer is a member of the family Flavobacteriaceae and a major causative agent of duck serositis. Little is known about its genetics and pathogenesis. Several bacteria are competent for natural transformation; however, whether R. anatipestifer is also competent for natural transformation has not been investigated. Here, we showed that R. anatipestifer strain ATCC 11845 can uptake the chromosomal DNA of R. anatipestifer strain RA-CH-1 in all growth phases. Subsequently, a natural transformation-based knockout method was established for R. anatipestifer ATCC 11845. Targeted mutagenesis gave transformation frequencies of ϳ10 Ϫ5 transformants. Competition assay experiments showed that R. anatipestifer ATCC 11845 preferentially took up its own DNA rather than heterogeneous DNA, such as Escherichia coli DNA. Transformation was less efficient with the shuttle plasmid pLMF03 (transformation frequencies of ϳ10 Ϫ9 transformants). However, the efficiency of transformation was increased approximately 100-fold using pLMF03 derivatives containing R. anatipestifer DNA fragments (transformation frequencies of ϳ10 Ϫ7 transformants). Finally, we found that the R. anatipestifer RA-CH-1 strain was also naturally transformable, suggesting that natural competence is widely applicable for this species. The findings described here provide important tools for the genetic manipulation of R. anatipestifer.IMPORTANCE Riemerella anatipestifer is an important duck pathogen that belongs to the family Flavobacteriaceae. At least 21 different serotypes have been identified. Genetic diversity has been demonstrated among these serotypes. The genetic and pathogenic mechanisms of R. anatipestifer remain largely unknown because no genetic tools are available for this bacterium. At present, natural transformation has been found in some bacteria but not in R. anatipestifer. For the first time, we showed that natural transformation occurred in R. anatipestifer ATCC 11845 and R. anatipestifer RA-CH-1. Then, we established an easy gene knockout method in R. anatipestifer based on natural transformation. This information is important for further studies of the genetic diversity and pathogenesis in R. anatipestifer.KEYWORDS Riemerella anatipestifer, natural transformation, targeted mutagenesis R iemerella anatipestifer is a Gram-negative, non-spore-forming, rod-shaped bacterium that is a major causative agent of septicemia in waterfowl, turkey, and other birds (1). R. anatipestifer infection leads to great economic losses due to its high mortality in ducklings and poor feed conversion (2). At present, at least 21 serotypes of

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Natural Transformation of Gallibacterium anatis

Abstract: ABSTRACTGallibacterium anatisis a pathogen of poultry. Very little is known about its genetics and pathogenesis. To enable the study of gene function inG. anatis, we have established methods for transformation and targeted mutagenesis. The genusGallibacteriumbelongs to th… Show more

Cited by 35 publications

References 39 publications

Genome Analysis and Phylogenetic Relatedness of Gallibacterium anatis Strains from Poultry

Genome Analysis and Phylogenetic Relatedness of Gallibacterium anatis Strains from Poultry

Natural Competence and the Evolution of DNA Uptake Specificity

Use of Natural Transformation To Establish an Easy Knockout Method in Riemerella anatipestifer

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