Gregg S. Pettis

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Capsular polysaccharide (CPS) is a major virulence factor in Vibrio vulnificus, and encapsulated strains have an opaque, smooth (OpS) colony morphology, while nonencapsulated strains have a translucent, smooth (TrS) colony morphology. Previously, we showed that OpS and TrS parental strains can yield a third colony type, rugose (R), and that the resulting(More)
Plant pathogenicity is rare in the genus Streptomyces, with only a dozen or so species possessing this trait out of the more than 900 species described. Nevertheless, such species have had a significant impact on agricultural economies throughout the world due to their ability to cause important crop diseases such as potato common scab, which is(More)
We previously have shown that a chromosomally integrated copy of the tra gene of plasmid pIJ101 under the control of the KorA repressor protein, which regulates transcription of tra as well as its own synthesis, can promote the conjugal transfer of both chromosomal and plasmid genes in Streptomyces lividans. Using an antibody generated against a fusion(More)
The tra gene of Streptomyces lividans plasmid pIJ101 encodes a 621-amino-acid protein that can mediate both plasmid transfer and the interbacterial transfer of chromosomal genes (i.e., chromosome-mobilizing ability [Cma]) during mating. Here we report the results of in-frame insertional mutagenesis studies aimed at defining regions of Tra required for these(More)
The tra gene of Streptomyces lividans plasmid plJ101 is required for both plasmid DNA transfer and plJ101-induced mobilization of chromosomal genes during mating. We show that a chromosomally inserted copy of tra mediates transfer of chromosomal DNA at high frequency but promotes efficient transfer of plasmids only when they contain a previously unknown(More)
The nucleotide sequence of the Escherichia coli enterobactin biosynthesis gene entD has been determined. entD specifies a predicted 23579 Dalton protein containing several helical regions, a transmembrane segment and one positively charged domain. The EntD polypeptide was overexpressed and identified in electrophoretic gels as a membrane protein. Although(More)
ABSTRACT Streptomyces soil rot is a destructive disease of sweetpotato (Ipomoea batatas) that causes yield loss resulting from decay of the feeder root system and reduced quality due to the presence of necrotic lesions on the storage roots. It is managed by the use of resistant cultivars, but variability of the pathogen has not been previously assessed.(More)
Efficient interbacterial transfer of streptomycete plasmid pIJ101 requires the pIJ101 tra gene, as well as a cis-acting plasmid function known as clt. Here we show that the minimal pIJ101 clt locus consists of a sequence no greater than 54 bp in size that includes essential inverted-repeat and direct-repeat sequences and is located in close proximity to the(More)
The marine bacterium Vibrio vulnificus is a human pathogen that can spontaneously switch between virulent opaque and avirulent translucent phenotypes. Here, we document an additional form, the rugose variant, which produces copious biofilms and which may contribute both to pathogenicity of V. vulnificus and to its survival under adverse environmental(More)
Plasmid pIJ101 from Streptomyces lividans encodes a single gene, tra, that is essential for both plasmid transfer and mobilization of chromosomes during mating. The tra gene product (Tra) is a membrane protein, a portion of which shows similarity to transfer proteins of other streptomycete plasmids as well as additional bacterial chromosome partitioning(More)