The Role of Short-Chain Conjugated Poly-(R)-3-Hydroxybutyrate (cPHB) in Protein Folding

Reusch, Rosetta N.

doi:10.3390/ijms140610727

Cited by 28 publications

(26 citation statements)

References 101 publications

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“…Biosynthesis of PHB starts with the condensation of two molecules of acetyl-CoA to acetoacetyl-CoA, which is subsequently reduced to (R)-3-hydroxybutanoyl-CoA. This latter compound is then polymerized to PHB (43). In agreement with the initial observations, metabolome analyses detected a constant increase of the PHB intermediate 3-hydroxybutanoate over time (supplemental Table S2).…”

Section: Adaptation Of the Electron Transfer Chains To Anoxic Conditisupporting

confidence: 76%

Gene Regulatory and Metabolic Adaptation Processes of Dinoroseobacter shibae DFL12T during Oxygen Depletion

Laaß

Kleist

Bill

et al. 2014

Journal of Biological Chemistry

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Background:The bacterium Dinoroseobacter shibae was exposed to environmental anoxia. Results: Systems biology analyses showed the time-resolved cellular adaptation processes of D. shibae during oxygen depletion. Conclusion:Oxygen depletion led to a metabolic crisis due to the missing regeneration of ATP and reduction equivalents, until denitrification was established. Significance: Here we have elucidated the adaptation processes of marine bacteria to anoxic respiration.

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Section: Adaptation Of the Electron Transfer Chains To Anoxic Conditisupporting

confidence: 76%

Gene Regulatory and Metabolic Adaptation Processes of Dinoroseobacter shibae DFL12T during Oxygen Depletion

Laaß

Kleist

Bill

et al. 2014

Journal of Biological Chemistry

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“…One should also consider the possibility that an enzyme with depolymerase activity on amorphous PHB could be involved in the hydrolysis of complex PHB (cPHB) or PHBylated proteins (oligo-PHB). cPHB and oligo-PHB are present in small amounts in all prokaryotic and eukaryotic organisms that have been looked at and can have important functions, e.g., in the modulation of enzyme activities and/or channel activities (45)(46)(47).…”

Section: Discussionmentioning

confidence: 99%

To Be or Not To Be a Poly(3-Hydroxybutyrate) (PHB) Depolymerase: PhaZd1 (PhaZ6) and PhaZd2 (PhaZ7) of Ralstonia eutropha, Highly Active PHB Depolymerases with No Detectable Role in Mobilization of Accumulated PHB

Sznajder

Jendrossek

2014

Appl Environ Microbiol

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The putative physiological functions of two related intracellular poly(3-hydroxybutyrate) (PHB) depolymerases, PhaZd1 and PhaZd2, of Ralstonia eutropha H16 were investigated. Purified PhaZd1 and PhaZd2 were active with native PHB granules in vitro. Partial removal of the proteinaceous surface layer of native PHB granules by trypsin treatment or the use of PHB granules isolated from ⌬phaP1 or ⌬phaP1-phaP5 mutant strains resulted in increased specific PHB depolymerase activity, especially for PhaZd2. Constitutive expression of PhaZd1 or PhaZd2 reduced or even prevented the accumulation of PHB under PHB-permissive conditions in vivo. Expression of translational fusions of enhanced yellow fluorescent protein (EYFP) with PhaZd1 and PhaZd2 in which the active-site serines (S190 and Ser193) were replaced with alanine resulted in the colocalization of only PhaZd1 fusions with PHB granules. C-terminal fusions of inactive PhaZd2(S193A) with EYFP revealed the presence of spindlelike structures, and no colocalization with PHB granules was observed. Chromosomal deletion of phaZd1, phaZd2, or both depolymerase genes had no significant effect on PHB accumulation and mobilization during growth in nutrient broth (NB) or NBgluconate medium. Moreover, neither proteome analysis of purified native PHB granules nor lacZ fusion studies gave any indication that PhaZd1 or PhaZd2 was detectably present in the PHB granule fraction or expressed at all during growth on NBgluconate medium. In conclusion, PhaZd1 and PhaZd2 are two PHB depolymerases with a high capacity to degrade PHB when artificially expressed but are apparently not involved in PHB mobilization in the wild type. The true in vivo functions of PhaZd1 and PhaZd2 remain obscure. Ralstonia eutropha H16 is a chemolithoautotrophic betaproteobacterium that has become famous because of its ability to accumulate large amounts of poly(3-hydroxybutyrate) (PHB). R. eutropha is used for the commercial production of bioplastics (polyhydroxyalkanoates [PHAs] such as PHB and copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate) and is considered a model organism for PHA research (1-5). Investigation of the composition of the surface layer of PHB granules of R. eutropha H16 revealed an astonishingly high number of polypeptides that are predicted or have already been shown to be specifically attached to the PHB granule surface. These proteins include enzymes involved in biosynthesis (PHB synthase PhaC1) (6), in granule structure integrity (phasins PhaP1-PhaP7), in PHB mobilization (PhaZa1 to PhaZa5, PhaZb, PhaZc, PhaZd), and in other functions (PhaR, PhaM). For reviews, see references 1, 5, 7, and 8. Other PHA-accumulating bacteria and Archaea are also known to have proteins specifically attached to the PHA surface (9-15). For an overview and more references, see Table 2 in reference 5. Unfortunately, designation of PHB granule-associated proteins in R. eutropha is not uniformly used in literature: for alternative designations of PHB depolymerases and PHB oligomer hydrolases in R. eutropha, s...

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“…Note the high number of outer membrane proteins. (Schubert et al, 1988;Slater et al, 1988;Peoples and Sinskey, 1989;Gerngross and Martin, 1995;Hiraishi et al, 2005;Peters et al, 2007;Jendrossek, 2009;2012;2013;Cho et al, 2012) phaC2* PHB synthase (gene not expressed)…”

Section: Phb Granule-associated Proteins (Pgaps)mentioning

confidence: 99%

New insights in the formation of polyhydroxyalkanoate granules (carbonosomes) and novel functions of poly(3‐hydroxybutyrate)

Jendrossek

Pfeiffer

2014

Environmental Microbiology

215

179

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SummaryThe metabolism of polyhydroxybutyrate (PHB) and related polyhydroxyalkanoates (PHAs) has been investigated by many groups for about three decades, and good progress was obtained in understanding the mechanisms of biosynthesis and biodegradation of this class of storage molecules. However, the molecular events that happen at the onset of PHB synthesis and the details of the initiation of PHB/PHA granule formation, as well as the complex composition of the proteinaceous surface layer of PHB/PHA granules, have only recently come into the focus of research and were not reviewed yet. In this contribution, we summarize the progress in understanding the initiation and formation of the PHA granule complex at the example of Ralstonia eutropha H16 (model organism of PHB-accumulating bacteria). Where appropriate, we include information on PHA granules of Pseudomonas putida as a representative species for medium-chain-length PHA-accumulating bacteria. We suggest to replace the previous micelle mode of PHB granule formation by the Scaffold Model in which the PHB synthase initiation complex is bound to the bacterial nucleoid. In the second part, we highlight data on other forms of PHB: oligo-PHB with ≈100 to 200 3-hydroxybutyrate (3HB) units and covalently bound PHB (cPHB) are unrelated in function to storage PHB but are presumably present in all living organisms, and therefore must be of fundamental importance.

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The Role of Short-Chain Conjugated Poly-(R)-3-Hydroxybutyrate (cPHB) in Protein Folding

Cited by 28 publications

References 101 publications

Gene Regulatory and Metabolic Adaptation Processes of Dinoroseobacter shibae DFL12T during Oxygen Depletion

Gene Regulatory and Metabolic Adaptation Processes of Dinoroseobacter shibae DFL12T during Oxygen Depletion

To Be or Not To Be a Poly(3-Hydroxybutyrate) (PHB) Depolymerase: PhaZd1 (PhaZ6) and PhaZd2 (PhaZ7) of Ralstonia eutropha, Highly Active PHB Depolymerases with No Detectable Role in Mobilization of Accumulated PHB

New insights in the formation of polyhydroxyalkanoate granules (carbonosomes) and novel functions of poly(3‐hydroxybutyrate)

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