Dataset Information

The fragment structure of a putative HsdR subunit of a type I restriction enzyme from Vibrio vulnificus YJ016: implications for DNA restriction and translocation activity.

ABSTRACT: Among four types of bacterial restriction enzymes that cleave a foreign DNA depending on its methylation status, type I enzymes composed of three subunits are interesting because of their unique DNA cleavage and translocation mechanisms performed by the restriction subunit (HsdR). The elucidated N-terminal fragment structure of a putative HsdR subunit from Vibrio vulnificus YJ016 reveals three globular domains. The nucleolytic core within an N-terminal nuclease domain (NTD) is composed of one basic and three acidic residues, which include a metal-binding site. An ATP hydrolase (ATPase) site at the interface of two RecA-like domains (RDs) is located close to the probable DNA-binding site for translocation, which is far from the NTD nucleolytic core. Comparison of relative domain arrangements with other functionally related ATP and/or DNA complex structures suggests a possible translocation and restriction mechanism of the HsdR subunit. Furthermore, careful analysis of its sequence and structure implies that a linker helix connecting two RDs and an extended region within the nuclease domain may play a central role in switching the DNA translocation into the restriction activity.

SUBMITTER: Uyen NT

PROVIDER: S-EPMC2777439 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

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The fragment structure of a putative HsdR subunit of a type I restriction enzyme from Vibrio vulnificus YJ016: implications for DNA restriction and translocation activity.

Uyen Nguyen To NT Park Suk-Youl SY Choi Ji-Woo JW Lee Hyun-Ju HJ Nishi Kosuke K Kim Jeong-Sun JS

Nucleic acids research 20090722 20

Among four types of bacterial restriction enzymes that cleave a foreign DNA depending on its methylation status, type I enzymes composed of three subunits are interesting because of their unique DNA cleavage and translocation mechanisms performed by the restriction subunit (HsdR). The elucidated N-terminal fragment structure of a putative HsdR subunit from Vibrio vulnificus YJ016 reveals three globular domains. The nucleolytic core within an N-terminal nuclease domain (NTD) is composed of one ba ...[more]

PMID: 19625490

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Project description:Type IV pili contribute to virulence in Vibrio vulnificus, the bacterium responsible for the majority of fatal seafood-related infections. Here, we performed within- and between-species evolutionary analysis of the gene that encodes the major structural subunit of the pilus, pilA, by comparing it with pilD and gyrB, the genes encoding the type IV prepilin peptidase and beta subunit of DNA gyrase, respectively. Although the diversity in pilD and gyrB is similar to each other and likely to have accumulated after speciation of V. vulnificus, pilA is several times more diverse at both nonsynonymous and synonymous levels. Also, in contrast to pilD and gyrB, there are virtually unrestricted and highly localized horizontal movements of pilA alleles between the major phylogenetic groups of V. vulnificus. The frequent movement of pilA involves homologous recombination of the entire gene with no evidence for intragenic recombination between the alleles. We propose that pilA allelic diversity and horizontal movement is maintained in the population by both diversifying and frequency-dependent selection most likely to escape shellfish innate immunity defense or lytic phages. Other possibilities leading to such selection dynamics of V. vulnificus pilA could involve adaptation to diverse host populations or within-host compartments, or natural DNA uptake and transformation. We show that the history of nucleotide diversification in pilA predates V. vulnificus speciation and this diversification started at or before the time of the last common ancestor for V. vulnificus, Vibrio parahaemolyticus, and Vibrio cholerae. At the same time, it appears that within the various pilA groups of V. vulnificus, there is no positive selection for structural mutations and consequently no evidence for source-sink selection. In contrast, pilD has accumulated a number of apparently adaptive mutations in the regions encoding the membrane-spanning portions of the prepilin peptidase, possibly affecting fimbrial expression and/or function, and is being subjected to source-sink selection dynamics.

Dataset Information

The fragment structure of a putative HsdR subunit of a type I restriction enzyme from Vibrio vulnificus YJ016: implications for DNA restriction and translocation activity.

Publications

The fragment structure of a putative HsdR subunit of a type I restriction enzyme from Vibrio vulnificus YJ016: implications for DNA restriction and translocation activity.

Similar Datasets

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