Characterization of phosphoproteins and protein kinase activity of virions, noninfectious enveloped particles, and dense bodies of human cytomegalovirus

Author:

Roby C,Gibson W

Abstract

Phosphorylation of the proteins of human cytomegalovirus (CMV) virions, noninfectious enveloped particles (NIEPs), and dense bodies was investigated. Analyses of particles phosphorylated in vivo showed the following. Virions contain three predominant phosphoproteins (i.e., basic phosphoprotein and upper and lower matrix proteins) and at least nine minor phosphorylated species. NIEPs contain all of these and one additional major species, the assembly protein. Dense bodies contain only one (i.e., lower matrix) of the predominant and four of the minor virion phosphoproteins. Two-dimensional (charge-size) separations in denaturing polyacrylamide gels showed that the relative net charges of the predominant phosphorylated species ranged from the basic phosphoprotein to the more neutral upper matrix protein. In vitro assays showed that purified virions of human CMV have an associated protein kinase activity. The activity was detected only after disrupting the envelope; it had a pH optimum of approximately 9 to 9.5 and required a divalent cation, preferring magnesium to manganese. In vitro, this activity catalyzed phosphorylation of the virion proteins observed to be phosphorylated in vivo. Peptide comparisons indicated that the sites phosphorylated in vitro are a subset of those phosphorylated in vivo, underscoring the probable biological relevance of the kinase activity. Casein, phosvitin, and to a minor extent lysine-rich histones served as exogenous phosphate acceptors. Arginine-rich and lysine-rich histones and protamine sulfate, as well as the polyamines spermine and spermidine, stimulated incorporation of phosphate into the endogenous viral proteins. Virions of all human and simian CMV strains tested showed this activity. Analyses of other virus particles, including three intracellular capsid forms (i.e., A, B, and C capsids), NIEPs, and dense bodies, indicated that the active enzyme was not present in the capsid. Rate-velocity sedimentation of disrupted virions separated the protein kinase activity into two fractions: one that phosphorylated exogenous casein and another that phosphorylated primarily the endogenous virion proteins.

Publisher

American Society for Microbiology

Subject

Virology,Insect Science,Immunology,Microbiology

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3