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J Biol Chem. 2019 Apr 12;294(15):6188-6203. doi: 10.1074/jbc.RA118.007049. Epub 2019 Feb 19.

Cyclins B1, T1, and H differ in their molecular mode of interaction with cytomegalovirus protein kinase pUL97.

Author information

1
From the Institute for Clinical and Molecular Virology, mirjam.steingruber@uk-erlangen.de.
2
From the Institute for Clinical and Molecular Virology.
3
Division of Bioinformatics, Institute of Biochemistry Friedrich-Alexander University of Erlangen-Nürnberg, 91054 Erlangen, Germany.
4
the Université Grenoble Alpes, CEA, Inserm, BIG-BGE, 38000 Grenoble, France, and.
5
the Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, 55131 Mainz, Germany.
6
Division of Bioinformatics, Institute of Biochemistry Friedrich-Alexander University of Erlangen-Nürnberg, 91054 Erlangen, Germany, heinrich.sticht@fau.de.
7
From the Institute for Clinical and Molecular Virology, manfred.marschall@fau.de.

Abstract

Human cytomegalovirus (HCMV) is a common β-herpesvirus causing life-long latent infections. HCMV replication interferes with cell cycle regulation in host cells because the HCMV-encoded cyclin-dependent kinase (CDK) ortholog pUL97 extensively phosphorylates the checkpoint regulator retinoblastoma protein. pUL97 also interacts with cyclins B1, T1, and H, and recent findings have strongly suggested that these interactions influence pUL97 substrate recognition. Interestingly, here we detected profound mechanistic differences among these pUL97-cyclin interactions. Our study revealed the following. (i) pUL97 interacts with cyclins B1 and H in a manner dependent on pUL97 activity and HCMV-specific cyclin modulation, respectively. (ii) The phosphorylated state of both proteins is an important determinant of the pUL97-cyclin B1 interaction. (iii) Activated phospho-Thr-315 cyclin H is up-regulated during HCMV replication. (iv) Thr-315 phosphorylation is independent of intracellular pUL97 or CDK7 activity. (v) pUL97-mediated in vitro phosphorylation is detectable for cyclin B1 but not H. (vi) Mutual transphosphorylation between pUL97 and CDK7 is not detectable, and an MS-based phosphosite analysis indicated that pUL97 might unexpectedly not be phosphorylated in its T-loop. (vii) The binary complexes pUL97-cyclin H and CDK7-cyclin H as well as the ternary complex pUL97-cyclin-H-CDK7 are detectable in an assembly-based CoIP approach. (viii) pUL97 self-interaction can be bridged by the transcriptional cyclins T1 or H but not by the classical cell cycle-regulating B1 cyclin. Combined, our findings unravel a number of cyclin type-specific differences in pUL97 interactions and suggest a multifaceted regulatory impact of cyclins on HCMV replication.

KEYWORDS:

cyclin; cyclins B1, T1, and H; human cytomegalovirus; phosphorylation; protein assembly; protein kinase; protein phosphorylation; regulatory interaction; reprogramming; viral kinase pUL97–cyclin complexes; viral replication

PMID:
30782840
PMCID:
PMC6463711
[Available on 2020-04-12]
DOI:
10.1074/jbc.RA118.007049

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