Dataset Information

Isolation and analysis of eight exe genes and their involvement in extracellular protein secretion and outer membrane assembly in Aeromonas hydrophila.

ABSTRACT: The exeE gene of Aeromonas hydrophila has been shown to be required for the secretion of most if not all of the extracellular proteins produced by this bacterium. In addition, an exeE::Tn5-751 insertion mutant of A. hydrophila was found to be deficient in the amounts of a number of its major outer membrane proteins (B. Jiang and S. P. Howard, J. Bacteriol. 173:1241-1249, 1991). The exeE gene and the exeF gene were previously isolated as part of a fragment which complemented this mutant. In this study, we have isolated and sequenced a further eight exe genes, exeG through exeN, which constitute the 3' end of the exe operon. These genes have a high degree of similarity with the extracellular secretion operons of a number of different gram-negative bacteria. Marker exchange mutagenesis was used to insert kanamycin resistance cassettes into three different regions of the exe operon. The phenotypes of these mutants showed that in A. hydrophila this operon is required not only for extracellular protein secretion but also for normal assembly of the outer membrane, in particular with respect to the quantities of the major porins. Five of the Exe proteins contain type IV prepilin signal sequences, although the prepilin peptidase gene does not appear to form part of the exe operon. Limited processing of the ExeG protein was observed when it was expressed in Escherichia coli, and this processing was greatly accelerated in the presence of the prepilin peptidase of Pseudomonas aeruginosa.

SUBMITTER: Howard SP

PROVIDER: S-EPMC206782 | biostudies-other | 1993 Oct

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Isolation and analysis of eight exe genes and their involvement in extracellular protein secretion and outer membrane assembly in Aeromonas hydrophila.

Howard S P SP Critch J J Bedi A A

Journal of bacteriology 19931001 20

The exeE gene of Aeromonas hydrophila has been shown to be required for the secretion of most if not all of the extracellular proteins produced by this bacterium. In addition, an exeE::Tn5-751 insertion mutant of A. hydrophila was found to be deficient in the amounts of a number of its major outer membrane proteins (B. Jiang and S. P. Howard, J. Bacteriol. 173:1241-1249, 1991). The exeE gene and the exeF gene were previously isolated as part of a fragment which complemented this mutant. In this ...[more]

PMID: 8407845

Similar Datasets

Project description:BackgroundHypervirulent Aeromonas hydrophila (vAh) is an emerging pathogen in freshwater aquaculture that results in the loss of over 3 million pounds of marketable channel catfish, Ictalurus punctatus, and channel catfish hybrids (I. punctatus, ♀ x blue catfish, I. furcatus, ♂) each year from freshwater catfish production systems in Alabama, U.S.A. vAh isolates are clonal in nature and are genetically unique from, and significantly more virulent than, traditional A. hydrophila isolates from fish. Even with the increased virulence, natural infections cannot be reproduced in aquaria challenges making it difficult to determine modes of infection and the pathophysiology behind the devastating mortalities that are commonly observed. Despite the intimate connection between environmental adaptation and plastic response, the role of environmental adaption on vAh pathogenicity and virulence has not been previously explored. In this study, secreted proteins of vAh cultured as free-living planktonic cells and within a biofilm were compared to elucidate the role of biofilm growth on virulence.ResultsFunctional proteolytic assays found significantly increased degradative activity in biofilm secretomes; in contrast, planktonic secretomes had significantly increased hemolytic activity, suggesting higher toxigenic potential. Intramuscular injection challenges in a channel catfish model showed that in vitro degradative activity translated into in vivo tissue destruction. Identification of secreted proteins by HPLC-MS/MS revealed the presence of many putative virulence proteins under both growth conditions. Biofilm grown vAh produced higher levels of proteolytic enzymes and adhesins, whereas planktonically grown cells secreted higher levels of toxins, porins, and fimbrial proteins.ConclusionsThis study is the first comparison of the secreted proteomes of vAh when grown in two distinct ecological niches. These data on the adaptive physiological response of vAh based on growth condition increase our understanding of how environmental niche partitioning could affect vAh pathogenicity and virulence. Increased secretion of colonization factors and degradative enzymes during biofilm growth and residency may increase bacterial attachment and host invasiveness, while increased secretion of hemolysins, porins, and other potential toxins under planktonic growth (or after host invasion) could result in increased host mortality. The results of this research underscore the need to use culture methods that more closely mimic natural ecological habitat growth to improve our understanding of vAh pathogenesis.

Dataset Information

Isolation and analysis of eight exe genes and their involvement in extracellular protein secretion and outer membrane assembly in Aeromonas hydrophila.

Publications

Isolation and analysis of eight exe genes and their involvement in extracellular protein secretion and outer membrane assembly in Aeromonas hydrophila.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets