title: Phylogenetic and functional analyses of a plant protein related to human B-cell receptor-associated proteins.
abstract: Human B-cell receptor-associated protein BAP31 (HsBAP31) is the endoplasmic reticulum-resident protein involved in protein sorting and transport as well as pro-apoptotic signaling. Plant orthologs of HsBAP31 termed 'plant BAP-like proteins' (PBL proteins) have thus far remained unstudied. Recently, the PBL protein from Nicotiana tabacum (NtPBL) was identified as an interactor of Nt-4/1, a plant protein known to interact with plant virus movement proteins and affect the long-distance transport of potato spindle tuber viroid (PSTVd) via the phloem. Here, we have compared the sequences of PBL proteins and studied the biochemical properties of NtPBL. Analysis of a number of fully sequenced plant genomes revealed that PBL-encoding genes represent a small multigene family with up to six members per genome. Two conserved motifs were identified in the C-terminal region of PBL proteins. The NtPBL C-terminal hydrophilic region (NtPBL-C) was expressed in bacterial cells, purified, and used for analysis of its RNA binding properties in vitro. In gel shift experiments, NtPBL-C was found to bind several tested RNAs, showing the most efficient binding to microRNA precursors (pre-miRNA) and less efficient interaction with PSTVd. Mutational analysis suggested that NtPBL-C has a composite RNA-binding site, with two conserved lysine residues in the most C-terminal protein region being involved in binding of pre-miRNA but not PSTVd RNA. Virus-mediated transient expression of NtPBL-C in plants resulted in stunting and leaf malformation, developmental abnormalities similar to those described previously for blockage of miRNA biogenesis/function. We hypothesize that the NtPBL protein represents a previously undiscovered component of the miRNA pathway.
authors: Department of Virology, Biological Faculty, Moscow State University, Moscow, 119992, Russia.
authors: Anastasia K
authors: AK
authors: Atabekova
authors: Department of Virology, Biological Faculty, Moscow State University, Moscow, 119992, Russia.
authors: Anna V
authors: AV
authors: Pankratenko
authors: Department of Virology, Biological Faculty, Moscow State University, Moscow, 119992, Russia.
authors: Svetlana S
authors: SS
authors: Makarova
authors: Department of Virology, Biological Faculty, Moscow State University, Moscow, 119992, Russia.
authors: Ekaterina A
authors: EA
authors: Lazareva
authors: Molecular Plant Pathology Laboratory, USDA-ARS, Beltsville, MD, 20705, USA.
authors: Robert A
authors: RA
authors: Owens
authors: Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119992, Russia; Sechenov First Moscow State Medical University, Institute of Molecular Medicine, Moscow, 119991, Russia.
authors: Andrey G
authors: AG
authors: Solovyev
authors: Department of Virology, Biological Faculty, Moscow State University, Moscow, 119992, Russia; Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119992, Russia. Electronic address: morozov@genebee.msu.su.
authors: Sergey Y
authors: SY
authors: Morozov
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D018745:Genome, Plant / Q000235:genetics; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D005810:Multigene Family; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000821:virology; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D010942:Plant Viruses / Q000235:genetics / Q000502:physiology; D011485:Protein Binding; D012313:RNA / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000821:virology; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D014772:Viroids / Q000235:genetics / Q000502:physiology
chemical_list: C091247:BCAP31 protein, human; D008565:Membrane Proteins; D035683:MicroRNAs; D010940:Plant Proteins; D012367:RNA, Viral; D011994:Recombinant Proteins; D012313:RNA
keywords: BAP31; Endoplasmic reticulum; Micro RNA; Plant protein; RNA binding; Transient protein expression