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Biosynthesis of storage compounds by Rhodococcus jostii RHA1 and global identification of genes involved in their metabolism.

Hernández MA, Mohn WW, Martínez E, Rost E, Alvarez AF, Alvarez HM - BMC Genomics (2008)

Bottom Line: Members of the genus Rhodococcus are frequently found in soil and other natural environments and are highly resistant to stresses common in those environments.Where possible, key amino acid residues in the above proteins (generally in active sites, effectors binding sites or substrate binding sites) were identified in order to support gene identification.An extensive capacity to synthesize and metabolize storage compounds appears to contribute versatility to RHA1 in its responses to environmental stresses.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro Regional de Investigación y Desarrollo Científico Tecnológico, Facultad de Ciencias Naturales, Universidad Nacional de Patagonia San Juan Bosco, Km 4-Ciudad Universitaria, 9000 Comodoro Rivadavia, Chubut, Argentina. mahernandez@unpata.edu.ar

ABSTRACT

Background: Members of the genus Rhodococcus are frequently found in soil and other natural environments and are highly resistant to stresses common in those environments. The accumulation of storage compounds permits cells to survive and metabolically adapt during fluctuating environmental conditions. The purpose of this study was to perform a genome-wide bioinformatic analysis of key genes encoding metabolism of diverse storage compounds by Rhodococcus jostii RHA1 and to examine its ability to synthesize and accumulate triacylglycerols (TAG), wax esters, polyhydroxyalkanoates (PHA), glycogen and polyphosphate (PolyP).

Results: We identified in the RHA1 genome: 14 genes encoding putative wax ester synthase/acyl-CoA:diacylglycerol acyltransferase enzymes (WS/DGATs) likely involved in TAG and wax esters biosynthesis; a total of 54 genes coding for putative lipase/esterase enzymes possibly involved in TAG and wax ester degradation; 3 sets of genes encoding PHA synthases and PHA depolymerases; 6 genes encoding key enzymes for glycogen metabolism, one gene coding for a putative polyphosphate kinase and 3 putative exopolyphosphatase genes. Where possible, key amino acid residues in the above proteins (generally in active sites, effectors binding sites or substrate binding sites) were identified in order to support gene identification. RHA1 cells grown under N-limiting conditions, accumulated TAG as the main storage compounds plus wax esters, PHA (with 3-hydroxybutyrate and 3-hydroxyvalerate monomers), glycogen and PolyP. Rhodococcus members were previously known to accumulate TAG, wax esters, PHAs and polyP, but this is the first report of glycogen accumulation in this genus.

Conclusion: RHA1 possess key genes to accumulate diverse storage compounds. Under nitrogen-limiting conditions lipids are the principal storage compounds. An extensive capacity to synthesize and metabolize storage compounds appears to contribute versatility to RHA1 in its responses to environmental stresses.

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Modified Loeffler's methylene blue staining of Rhodococcus jostii RHA1 grown on MSM0.1 with gluconate 1% (w/v). (A) General view of cells by optic microscopy (1,000 ×). (B) and (C) Magnified views of cells showing dark stained polyP inclusions and lightly stained cytoplasm. These photographs have been digitally processed to increase magnification (Original magnification: 1,000 ×).
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Figure 6: Modified Loeffler's methylene blue staining of Rhodococcus jostii RHA1 grown on MSM0.1 with gluconate 1% (w/v). (A) General view of cells by optic microscopy (1,000 ×). (B) and (C) Magnified views of cells showing dark stained polyP inclusions and lightly stained cytoplasm. These photographs have been digitally processed to increase magnification (Original magnification: 1,000 ×).

Mentions: The occurrence of putative a ppk gene in the genome of strain RHA1 suggests that this bacterium has the potential to synthesize PolyP, like other members of Rhodococcus [6]. In addition, PolyP is likely mobilized by RHA1 cells using PPX-related proteins. In order to confirm the ability of strain RHA1 to accumulate PolyP, we analyzed cells by microscopy after cultivation on gluconate as the sole carbon source under N-limiting conditions. PolyP-bodies were observed in RHA1 cells as dark granules in contrast to a light red cell background by means of a modification of the methylene-blue staining method (Fig. 6). Identical results were observed with cells of R. opacus PD630 used as positive control, which was previously shown to accumulate PolyP [6].


Biosynthesis of storage compounds by Rhodococcus jostii RHA1 and global identification of genes involved in their metabolism.

Hernández MA, Mohn WW, Martínez E, Rost E, Alvarez AF, Alvarez HM - BMC Genomics (2008)

Modified Loeffler's methylene blue staining of Rhodococcus jostii RHA1 grown on MSM0.1 with gluconate 1% (w/v). (A) General view of cells by optic microscopy (1,000 ×). (B) and (C) Magnified views of cells showing dark stained polyP inclusions and lightly stained cytoplasm. These photographs have been digitally processed to increase magnification (Original magnification: 1,000 ×).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2667194&req=5

Figure 6: Modified Loeffler's methylene blue staining of Rhodococcus jostii RHA1 grown on MSM0.1 with gluconate 1% (w/v). (A) General view of cells by optic microscopy (1,000 ×). (B) and (C) Magnified views of cells showing dark stained polyP inclusions and lightly stained cytoplasm. These photographs have been digitally processed to increase magnification (Original magnification: 1,000 ×).
Mentions: The occurrence of putative a ppk gene in the genome of strain RHA1 suggests that this bacterium has the potential to synthesize PolyP, like other members of Rhodococcus [6]. In addition, PolyP is likely mobilized by RHA1 cells using PPX-related proteins. In order to confirm the ability of strain RHA1 to accumulate PolyP, we analyzed cells by microscopy after cultivation on gluconate as the sole carbon source under N-limiting conditions. PolyP-bodies were observed in RHA1 cells as dark granules in contrast to a light red cell background by means of a modification of the methylene-blue staining method (Fig. 6). Identical results were observed with cells of R. opacus PD630 used as positive control, which was previously shown to accumulate PolyP [6].

Bottom Line: Members of the genus Rhodococcus are frequently found in soil and other natural environments and are highly resistant to stresses common in those environments.Where possible, key amino acid residues in the above proteins (generally in active sites, effectors binding sites or substrate binding sites) were identified in order to support gene identification.An extensive capacity to synthesize and metabolize storage compounds appears to contribute versatility to RHA1 in its responses to environmental stresses.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro Regional de Investigación y Desarrollo Científico Tecnológico, Facultad de Ciencias Naturales, Universidad Nacional de Patagonia San Juan Bosco, Km 4-Ciudad Universitaria, 9000 Comodoro Rivadavia, Chubut, Argentina. mahernandez@unpata.edu.ar

ABSTRACT

Background: Members of the genus Rhodococcus are frequently found in soil and other natural environments and are highly resistant to stresses common in those environments. The accumulation of storage compounds permits cells to survive and metabolically adapt during fluctuating environmental conditions. The purpose of this study was to perform a genome-wide bioinformatic analysis of key genes encoding metabolism of diverse storage compounds by Rhodococcus jostii RHA1 and to examine its ability to synthesize and accumulate triacylglycerols (TAG), wax esters, polyhydroxyalkanoates (PHA), glycogen and polyphosphate (PolyP).

Results: We identified in the RHA1 genome: 14 genes encoding putative wax ester synthase/acyl-CoA:diacylglycerol acyltransferase enzymes (WS/DGATs) likely involved in TAG and wax esters biosynthesis; a total of 54 genes coding for putative lipase/esterase enzymes possibly involved in TAG and wax ester degradation; 3 sets of genes encoding PHA synthases and PHA depolymerases; 6 genes encoding key enzymes for glycogen metabolism, one gene coding for a putative polyphosphate kinase and 3 putative exopolyphosphatase genes. Where possible, key amino acid residues in the above proteins (generally in active sites, effectors binding sites or substrate binding sites) were identified in order to support gene identification. RHA1 cells grown under N-limiting conditions, accumulated TAG as the main storage compounds plus wax esters, PHA (with 3-hydroxybutyrate and 3-hydroxyvalerate monomers), glycogen and PolyP. Rhodococcus members were previously known to accumulate TAG, wax esters, PHAs and polyP, but this is the first report of glycogen accumulation in this genus.

Conclusion: RHA1 possess key genes to accumulate diverse storage compounds. Under nitrogen-limiting conditions lipids are the principal storage compounds. An extensive capacity to synthesize and metabolize storage compounds appears to contribute versatility to RHA1 in its responses to environmental stresses.

Show MeSH
Related in: MedlinePlus