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Protocol for detecting histidine polyphosphate modification of human proteins via MBP-tagged expression in E. coli.

ABSTRACT: Polyphosphate exhibits a unique post-translational modification-like function, known as histidine polyphosphate modification (HPM), marked by a robust non-covalent interaction with histidine repeat proteins. Here, we present a protocol for detecting HPM of human proteins via maltose-binding protein-tagged expression in E. coli. We describe steps for detecting HPM by observing electrophoretic mobility shifts on NuPAGE gels followed by western blot. We then detail procedures for analyzing the influence of ionic strength and pH on HPM. For complete details on the use and execution of this protocol, please refer to Neville et al.¹.

SUBMITTER: Lehotsky K

PROVIDER: S-EPMC10943961 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature

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Protocol for detecting histidine polyphosphate modification of human proteins via MBP-tagged expression in E. coli.

Lehotsky Kirsten K Neville Nolan N Jia Zongchao Z

STAR protocols 20240311 2

Polyphosphate exhibits a unique post-translational modification-like function, known as histidine polyphosphate modification (HPM), marked by a robust non-covalent interaction with histidine repeat proteins. Here, we present a protocol for detecting HPM of human proteins via maltose-binding protein-tagged expression in E. coli. We describe steps for detecting HPM by observing electrophoretic mobility shifts on NuPAGE gels followed by western blot. We then detail procedures for analyzing the infl ...[more]

PMID: 38470910

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Project description:On the basis of bioinformatic evidence, we suspected that proteins with a CYTH (CyaB thiamine triphosphatase) domain and/or a CHAD (conserved histidine α-helical domain) motif might represent polyphosphate (polyP) granule-associated proteins. We found no evidence of polyP targeting by proteins with CYTH domains. In contrast, two CHAD motif-containing proteins from Ralstonia eutropha H16 (A0104 and B1017) that were expressed as fusions with enhanced yellow fluorescent protein (eYFP) colocalized with polyP granules. While the expression of B1017 was not detectable, the A0104 protein was specifically identified in an isolated polyP granule fraction by proteome analysis. Moreover, eYFP fusions with the CHAD motif-containing proteins MGMSRV2-1987 from Magnetospirillum gryphiswaldense and PP2307 from Pseudomonas putida also colocalized with polyP granules in a transspecies-specific manner. These data indicated that CHAD-containing proteins are generally attached to polyP granules. Together with the findings from four previously polyP-attached proteins (polyP kinases), the results of this study raised the number of polyP-associated proteins in R. eutropha to six. We suggest designating polyP granule-bound proteins with CHAD motifs as phosins (phosphate), analogous to phasins and oleosins that are specifically bound to the surface of polyhydroxyalkanoate (PHA) granules in PHA-accumulating bacteria and to oil droplets in oil seed plants, respectively.IMPORTANCE The importance of polyphosphate (polyP) for life is evident from the ubiquitous presence of polyP in all species on earth. In unicellular eukaryotic microorganisms, polyP is located in specific membrane-enclosed organelles, called acidocalcisomes. However, in most prokaryotes, polyP is present as insoluble granules that have been designated previously as volutin granules. Almost nothing is known regarding the macromolecular composition of polyP granules. Particularly, the absence or presence of cellular compounds on the surface of polyP granules has not yet been investigated. In this study, we identified a novel class of proteins that are attached to the surface of polyP granules in three model species of Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria These proteins are characterized by the presence of a CHAD (conserved histidine α-helical domain) motif that functions as a polyP granule-targeting signal. We suggest designating CHAD motif-containing proteins as phosins [analogous to phasins for poly(3-hydroxybutyrate)-associated proteins and to oleosins for oil droplet-associated proteins in oil seed plants]. The expression of phosins in different species confirmed their polyP-targeting function in a transspecies-specific manner. We postulate that polyP granules in prokaryotic species generally have a complex surface structure that consists of one to several polyP kinases and phosin proteins. We suggest differentiating polyP granules from acidocalcisomes by designating them as polyphosphatosomes.

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Protocol for detecting histidine polyphosphate modification of human proteins via MBP-tagged expression in E. coli.

Publications

Protocol for detecting histidine polyphosphate modification of human proteins via MBP-tagged expression in E. coli.

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