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Deciphering the genome of polyphosphate accumulating actinobacterium Microlunatus phosphovorus.

Kawakoshi A, Nakazawa H, Fukada J, Sasagawa M, Katano Y, Nakamura S, Hosoyama A, Sasaki H, Ichikawa N, Hanada S, Kamagata Y, Nakamura K, Yamazaki S, Fujita N - DNA Res. (2012)

Bottom Line: The number of genes for polyP metabolism was greater in M. phosphovorus than in other actinobacteria; it possesses genes for four polyP kinases (ppks), two polyP-dependent glucokinases (ppgks), and three phosphate transporters (pits).Furthermore, M. phosphovorus lacks the phaABC genes for PHA synthesis and the actP gene encoding an acetate/H(+) symporter, both of which play crucial roles in anaerobic PHA accumulation in proteobacterial PAOs.Thus, while the general features of M. phosphovorus regarding aerobic polyP accumulation are similar to those of proteobacterial PAOs, its anaerobic polyP use and PHA synthesis appear to be different.

View Article: PubMed Central - PubMed

Affiliation: Biological Resource Center, National Institute of Technology and Evaluation, 2-10-49 Nishihara, Tokyo 151-0066, Japan.

ABSTRACT
Polyphosphate accumulating organisms (PAOs) belong mostly to Proteobacteria and Actinobacteria and are quite divergent. Under aerobic conditions, they accumulate intracellular polyphosphate (polyP), while they typically synthesize polyhydroxyalkanoates (PHAs) under anaerobic conditions. Many ecological, physiological, and genomic analyses have been performed with proteobacterial PAOs, but few with actinobacterial PAOs. In this study, the whole genome sequence of an actinobacterial PAO, Microlunatus phosphovorus NM-1(T) (NBRC 101784(T)), was determined. The number of genes for polyP metabolism was greater in M. phosphovorus than in other actinobacteria; it possesses genes for four polyP kinases (ppks), two polyP-dependent glucokinases (ppgks), and three phosphate transporters (pits). In contrast, it harbours only a single ppx gene for exopolyphosphatase, although two copies of ppx are generally present in other actinobacteria. Furthermore, M. phosphovorus lacks the phaABC genes for PHA synthesis and the actP gene encoding an acetate/H(+) symporter, both of which play crucial roles in anaerobic PHA accumulation in proteobacterial PAOs. Thus, while the general features of M. phosphovorus regarding aerobic polyP accumulation are similar to those of proteobacterial PAOs, its anaerobic polyP use and PHA synthesis appear to be different.

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Two independent pathways for PHA synthesis through (A) the PhaABC system, and (B) the β-oxidation pathway. Enzymes for which putative genes were predicted in the M. phosphovorus genome are shadowed.
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DSS020F4: Two independent pathways for PHA synthesis through (A) the PhaABC system, and (B) the β-oxidation pathway. Enzymes for which putative genes were predicted in the M. phosphovorus genome are shadowed.

Mentions: In addition to aerobic polyP accumulation, anaerobic PHA production is a recognized feature of PAOs.3 Recently, Aker et al.17 reported the detection in M. phosphovorus NM-1T cells of two PHA species, polyhydroxybutyrate and polyhydroxyvalerate, by Sudan Black B- and Safranin O-staining and gas chromatography methods. However, the system of PHA production in M. phosphovorus appears to be different from that proposed in proteobacterial PAOs; M. phosphovorus apparently produces PHA under aerobic conditions, whereas proteobacterial PAOs are believed to synthesize PHAs anaerobically. In proteobacterial PAOs, PHA is produced using glycogen/glucose or volatile fatty acids such as acetate as substrates, and the uptake of the acetate is conducted via ActP, a proteobacteria-specific acetate/H+ symporter. Acetate uptake through ActP is hypothesized to be counterbalanced by Pi release via Pit using the proton motive force.58,59 The intermediate acetyl-CoA is then converted to PHAs by acetyl-CoA acetyltransferase (PhaA), acetoacetyl-CoA reductase (PhaB), and PHA-synthase (PhaC) (Fig. 4).60 This model was further supported in a proteobacterial PAO, ‘Ca. Accumulibacter phosphatis’, by metagenomic and metaproteomic analyses.9,11 In contrast, neither actP nor phaABC exists in most actinobacteria, and these genes were not found in the M. phosphovorus genome either.Figure 4.


Deciphering the genome of polyphosphate accumulating actinobacterium Microlunatus phosphovorus.

Kawakoshi A, Nakazawa H, Fukada J, Sasagawa M, Katano Y, Nakamura S, Hosoyama A, Sasaki H, Ichikawa N, Hanada S, Kamagata Y, Nakamura K, Yamazaki S, Fujita N - DNA Res. (2012)

Two independent pathways for PHA synthesis through (A) the PhaABC system, and (B) the β-oxidation pathway. Enzymes for which putative genes were predicted in the M. phosphovorus genome are shadowed.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3473371&req=5

DSS020F4: Two independent pathways for PHA synthesis through (A) the PhaABC system, and (B) the β-oxidation pathway. Enzymes for which putative genes were predicted in the M. phosphovorus genome are shadowed.
Mentions: In addition to aerobic polyP accumulation, anaerobic PHA production is a recognized feature of PAOs.3 Recently, Aker et al.17 reported the detection in M. phosphovorus NM-1T cells of two PHA species, polyhydroxybutyrate and polyhydroxyvalerate, by Sudan Black B- and Safranin O-staining and gas chromatography methods. However, the system of PHA production in M. phosphovorus appears to be different from that proposed in proteobacterial PAOs; M. phosphovorus apparently produces PHA under aerobic conditions, whereas proteobacterial PAOs are believed to synthesize PHAs anaerobically. In proteobacterial PAOs, PHA is produced using glycogen/glucose or volatile fatty acids such as acetate as substrates, and the uptake of the acetate is conducted via ActP, a proteobacteria-specific acetate/H+ symporter. Acetate uptake through ActP is hypothesized to be counterbalanced by Pi release via Pit using the proton motive force.58,59 The intermediate acetyl-CoA is then converted to PHAs by acetyl-CoA acetyltransferase (PhaA), acetoacetyl-CoA reductase (PhaB), and PHA-synthase (PhaC) (Fig. 4).60 This model was further supported in a proteobacterial PAO, ‘Ca. Accumulibacter phosphatis’, by metagenomic and metaproteomic analyses.9,11 In contrast, neither actP nor phaABC exists in most actinobacteria, and these genes were not found in the M. phosphovorus genome either.Figure 4.

Bottom Line: The number of genes for polyP metabolism was greater in M. phosphovorus than in other actinobacteria; it possesses genes for four polyP kinases (ppks), two polyP-dependent glucokinases (ppgks), and three phosphate transporters (pits).Furthermore, M. phosphovorus lacks the phaABC genes for PHA synthesis and the actP gene encoding an acetate/H(+) symporter, both of which play crucial roles in anaerobic PHA accumulation in proteobacterial PAOs.Thus, while the general features of M. phosphovorus regarding aerobic polyP accumulation are similar to those of proteobacterial PAOs, its anaerobic polyP use and PHA synthesis appear to be different.

View Article: PubMed Central - PubMed

Affiliation: Biological Resource Center, National Institute of Technology and Evaluation, 2-10-49 Nishihara, Tokyo 151-0066, Japan.

ABSTRACT
Polyphosphate accumulating organisms (PAOs) belong mostly to Proteobacteria and Actinobacteria and are quite divergent. Under aerobic conditions, they accumulate intracellular polyphosphate (polyP), while they typically synthesize polyhydroxyalkanoates (PHAs) under anaerobic conditions. Many ecological, physiological, and genomic analyses have been performed with proteobacterial PAOs, but few with actinobacterial PAOs. In this study, the whole genome sequence of an actinobacterial PAO, Microlunatus phosphovorus NM-1(T) (NBRC 101784(T)), was determined. The number of genes for polyP metabolism was greater in M. phosphovorus than in other actinobacteria; it possesses genes for four polyP kinases (ppks), two polyP-dependent glucokinases (ppgks), and three phosphate transporters (pits). In contrast, it harbours only a single ppx gene for exopolyphosphatase, although two copies of ppx are generally present in other actinobacteria. Furthermore, M. phosphovorus lacks the phaABC genes for PHA synthesis and the actP gene encoding an acetate/H(+) symporter, both of which play crucial roles in anaerobic PHA accumulation in proteobacterial PAOs. Thus, while the general features of M. phosphovorus regarding aerobic polyP accumulation are similar to those of proteobacterial PAOs, its anaerobic polyP use and PHA synthesis appear to be different.

Show MeSH
Related in: MedlinePlus