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Functional Genomics of the Aeromonas salmonicida Lipopolysaccharide O-Antigen and A-Layer from Typical and Atypical Strains.

Merino S, de Mendoza E, Canals R, Tomás JM - Mar Drugs (2015)

Bottom Line: Between genes of the wbsalmo we found the genes responsible for the biosynthesis and assembly of the S-layer (named A-layer in these strains).Through comparative genomic analysis and in-frame deletions of some of the genes, we concluded that all the A. salmonicida typical and atypical strains, other than A. salmonicida subsp. pectinolytica strains, shared the same wbsalmo and presence of A-layer.A. salmonicida subsp. pectinolytica strains lack wbsalmo and A-layer, two major virulence factors, and this could be the reason they are the only ones not found as fish pathogens.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Faculty of Biology, University of Barcelona, Diagonal 643, Barcelona 08071, Spain. smerino@ub.edu.

ABSTRACT
The A. salmonicida A450 LPS O-antigen, encoded by the wbsalmo gene cluster, is exported through an ABC-2 transporter-dependent pathway. It represents the first example of an O-antigen LPS polysaccharide with three different monosaccharides in their repeating unit assembled by this pathway. Until now, only repeating units with one or two different monosaccharides have been described. Functional genomic analysis of this wbsalmo region is mostly in agreement with the LPS O-antigen structure of acetylated l-rhamnose (Rha), d-glucose (Glc), and 2-amino-2-deoxy-d-mannose (ManN). Between genes of the wbsalmo we found the genes responsible for the biosynthesis and assembly of the S-layer (named A-layer in these strains). Through comparative genomic analysis and in-frame deletions of some of the genes, we concluded that all the A. salmonicida typical and atypical strains, other than A. salmonicida subsp. pectinolytica strains, shared the same wbsalmo and presence of A-layer. A. salmonicida subsp. pectinolytica strains lack wbsalmo and A-layer, two major virulence factors, and this could be the reason they are the only ones not found as fish pathogens.

No MeSH data available.


PCR amplified band (696 bp) with primers VapA-for: 5′-ATCGACAGCAATGGCAAG-3′ and VapA-rev: 5′-ATCACGGGTGAGGATGAAG-3′ and A. salmonicida genomic DNAs from strains: subspecies salmonicida A450 (lane 2), subspecies masoucida CECT4235 (lane 3), subspecies achromogenes CECT4238 (lane 4), subspecies smithia CECT5179 (lane 5), subspecies pectinolytica CECT5752T (lane 6), and subspecies pectinolytica CECT5753 (lane 7). Lane 1, DNA molecular weight standard.
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marinedrugs-13-03791-f006: PCR amplified band (696 bp) with primers VapA-for: 5′-ATCGACAGCAATGGCAAG-3′ and VapA-rev: 5′-ATCACGGGTGAGGATGAAG-3′ and A. salmonicida genomic DNAs from strains: subspecies salmonicida A450 (lane 2), subspecies masoucida CECT4235 (lane 3), subspecies achromogenes CECT4238 (lane 4), subspecies smithia CECT5179 (lane 5), subspecies pectinolytica CECT5752T (lane 6), and subspecies pectinolytica CECT5753 (lane 7). Lane 1, DNA molecular weight standard.

Mentions: When we inspected and deeply studied all the currently available A. salmonicida genomes, we found that the wbsalmo was conserved in all of the different subspecies with identical gene location besides in A. salmonicida subsp. pectinolytica. This fact is in full agreement with the LPS profiles in SDS-PAGE obtained for the different A. salmonicida strains from several subspecies. Sequence analysis of the A. salmonicida subsp. pectinolyticawb gene cluster from strain 34melT revealed that the LPS O-antigen seems to be exported through a Wzx-Wzy pathway and not an ABC-2 transporter-dependent pathway. However, besides the presence of the typical genes encoding the Wzx and Wzz proteins, no gene encoding a Wzy protein could be found in this cluster. Wzy mutants showed only a single O-antigen repeating unit [9] and, in the case of the LPS profile of A. salmonicida subsp. pectinolytica strains, it seems that a single O-antigen unit could be observed. A. salmonicida subsp. pectinolytica strains clearly show a different O-antigen LPS compared to the other subspecies and lack the A-layer according to our results. No such A-layer protein encoded by vapA gene could be detected by blot hybridization or PCR using appropriate DNA primers (Figure 6). This gene could not be found in the complete genome of A. salmonicida subsp pectinolytica strain 34melT.


Functional Genomics of the Aeromonas salmonicida Lipopolysaccharide O-Antigen and A-Layer from Typical and Atypical Strains.

Merino S, de Mendoza E, Canals R, Tomás JM - Mar Drugs (2015)

PCR amplified band (696 bp) with primers VapA-for: 5′-ATCGACAGCAATGGCAAG-3′ and VapA-rev: 5′-ATCACGGGTGAGGATGAAG-3′ and A. salmonicida genomic DNAs from strains: subspecies salmonicida A450 (lane 2), subspecies masoucida CECT4235 (lane 3), subspecies achromogenes CECT4238 (lane 4), subspecies smithia CECT5179 (lane 5), subspecies pectinolytica CECT5752T (lane 6), and subspecies pectinolytica CECT5753 (lane 7). Lane 1, DNA molecular weight standard.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4483657&req=5

marinedrugs-13-03791-f006: PCR amplified band (696 bp) with primers VapA-for: 5′-ATCGACAGCAATGGCAAG-3′ and VapA-rev: 5′-ATCACGGGTGAGGATGAAG-3′ and A. salmonicida genomic DNAs from strains: subspecies salmonicida A450 (lane 2), subspecies masoucida CECT4235 (lane 3), subspecies achromogenes CECT4238 (lane 4), subspecies smithia CECT5179 (lane 5), subspecies pectinolytica CECT5752T (lane 6), and subspecies pectinolytica CECT5753 (lane 7). Lane 1, DNA molecular weight standard.
Mentions: When we inspected and deeply studied all the currently available A. salmonicida genomes, we found that the wbsalmo was conserved in all of the different subspecies with identical gene location besides in A. salmonicida subsp. pectinolytica. This fact is in full agreement with the LPS profiles in SDS-PAGE obtained for the different A. salmonicida strains from several subspecies. Sequence analysis of the A. salmonicida subsp. pectinolyticawb gene cluster from strain 34melT revealed that the LPS O-antigen seems to be exported through a Wzx-Wzy pathway and not an ABC-2 transporter-dependent pathway. However, besides the presence of the typical genes encoding the Wzx and Wzz proteins, no gene encoding a Wzy protein could be found in this cluster. Wzy mutants showed only a single O-antigen repeating unit [9] and, in the case of the LPS profile of A. salmonicida subsp. pectinolytica strains, it seems that a single O-antigen unit could be observed. A. salmonicida subsp. pectinolytica strains clearly show a different O-antigen LPS compared to the other subspecies and lack the A-layer according to our results. No such A-layer protein encoded by vapA gene could be detected by blot hybridization or PCR using appropriate DNA primers (Figure 6). This gene could not be found in the complete genome of A. salmonicida subsp pectinolytica strain 34melT.

Bottom Line: Between genes of the wbsalmo we found the genes responsible for the biosynthesis and assembly of the S-layer (named A-layer in these strains).Through comparative genomic analysis and in-frame deletions of some of the genes, we concluded that all the A. salmonicida typical and atypical strains, other than A. salmonicida subsp. pectinolytica strains, shared the same wbsalmo and presence of A-layer.A. salmonicida subsp. pectinolytica strains lack wbsalmo and A-layer, two major virulence factors, and this could be the reason they are the only ones not found as fish pathogens.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Faculty of Biology, University of Barcelona, Diagonal 643, Barcelona 08071, Spain. smerino@ub.edu.

ABSTRACT
The A. salmonicida A450 LPS O-antigen, encoded by the wbsalmo gene cluster, is exported through an ABC-2 transporter-dependent pathway. It represents the first example of an O-antigen LPS polysaccharide with three different monosaccharides in their repeating unit assembled by this pathway. Until now, only repeating units with one or two different monosaccharides have been described. Functional genomic analysis of this wbsalmo region is mostly in agreement with the LPS O-antigen structure of acetylated l-rhamnose (Rha), d-glucose (Glc), and 2-amino-2-deoxy-d-mannose (ManN). Between genes of the wbsalmo we found the genes responsible for the biosynthesis and assembly of the S-layer (named A-layer in these strains). Through comparative genomic analysis and in-frame deletions of some of the genes, we concluded that all the A. salmonicida typical and atypical strains, other than A. salmonicida subsp. pectinolytica strains, shared the same wbsalmo and presence of A-layer. A. salmonicida subsp. pectinolytica strains lack wbsalmo and A-layer, two major virulence factors, and this could be the reason they are the only ones not found as fish pathogens.

No MeSH data available.