title: Functional and Structural Characterization of Novel Type of Linker Connecting Capsid and Nucleocapsid Protein Domains in Murine Leukemia Virus.
abstract: The assembly of immature retroviral particles is initiated in the cytoplasm by the binding of the structural polyprotein precursor Gag with viral genomic RNA. The protein interactions necessary for assembly are mediated predominantly by the capsid (CA) and nucleocapsid (NC) domains, which have conserved structures. In contrast, the structural arrangement of the CA-NC connecting region differs between retroviral species. In HIV-1 and Rous sarcoma virus, this region forms a rod-like structure that separates the CA and NC domains, whereas in Mason-Pfizer monkey virus, this region is densely packed, thus holding the CA and NC domains in close proximity. Interestingly, the sequence connecting the CA and NC domains in gammaretroviruses, such as murine leukemia virus (MLV), is unique. The sequence is called a charged assembly helix (CAH) due to a high number of positively and negatively charged residues. Although both computational and deletion analyses suggested that the MLV CAH forms a helical conformation, no structural or biochemical data supporting this hypothesis have been published. Using an in vitro assembly assay, alanine scanning mutagenesis, and biophysical techniques (circular dichroism, NMR, microcalorimetry, and electrophoretic mobility shift assay), we have characterized the structure and function of the MLV CAH. We provide experimental evidence that the MLV CAH belongs to a group of charged, E(R/K)-rich, single α-helices. This is the first single α-helix motif identified in viral proteins.
authors: From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 16610 Prague 6.
authors: Michal
authors: M
authors: Doležal
authors: From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 16610 Prague 6.
authors: Romana
authors: R
authors: Hadravová
authors: From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 16610 Prague 6.
authors: Milan
authors: M
authors: Kožíšek
authors: From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 16610 Prague 6.
authors: Lucie
authors: L
authors: Bednárová
authors: the Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Technická 3, 166 28 Prague, and.
authors: Hana
authors: H
authors: Langerová
authors: the Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Technická 3, 166 28 Prague, and.
authors: Tomáš
authors: T
authors: Ruml
authors: From the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 16610 Prague 6, the Department of Biotechnology, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic michaela.rumlova@vscht.cz.
authors: Michaela
authors: M
authors: Rumlová
mesh_terms: D000818:Animals; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics; D009052:Leukemia Virus, Murine / Q000737:chemistry* / Q000235:genetics; D051379:Mice; D016296:Mutagenesis; D000072417:Protein Domains; D017433:Protein Structure, Secondary
chemical_list: D036022:Capsid Proteins
keywords: capsid protein (CA); charged assembly helix (CAH); circular dichroism (CD); electron microscopy (EM); murine leukemia virus (MLV); nuclear magnetic resonance (NMR); retrovirus; single alpha-helix (SAH); spacer peptide (SP); virus assembly