Yamaguchi A, Iwatani M, Ogawa M, Kitano H, Matsuyama M. In vitro characterization of the RS motif in N-terminal head domain of goldfish germinal vesicle lamin B3 necessary for phosphorylation of the p34cdc2 target serine by SRPK1.
FEBS Open Bio 2013;
3:165-76. [PMID:
23772390 PMCID:
PMC3668540 DOI:
10.1016/j.fob.2013.03.003]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/20/2013] [Accepted: 03/21/2013] [Indexed: 11/28/2022] Open
Abstract
The nuclear envelopes surrounding the oocyte germinal vesicles of lower vertebrates (fish and frog) are supported by the lamina, which consists of the protein lamin B3 encoded by a gene found also in birds but lost in the lineage leading to mammals. Like other members of the lamin family, goldfish lamin B3 (gfLB3) contains two putative consensus phosphoacceptor p34cdc2 sites (Ser-28 and Ser-398) for the M-phase kinase to regulate lamin polymerization on the N- and C-terminal regions flanking a central rod domain. Partial phosphorylation of gfLB3 occurs on Ser-28 in the N-terminal head domain in immature oocytes prior to germinal vesicle breakdown, which suggests continual rearrangement of lamins by a novel lamin kinase in fish oocytes. We applied the expression-screening method to isolate lamin kinases by using phosphorylation site Ser-28-specific monoclonal antibody and a vector encoding substrate peptides from a goldfish ovarian cDNA library. As a result, SRPK1 was screened as a prominent lamin kinase candidate. The gfLB3 has a short stretch of the RS repeats (9-SRASTVRSSRRS-20) upstream of the Ser-28, within the N-terminal head. This stretch of repeats is conserved among fish lamin B3 but is not found in other lamins. In vitro phosphorylation studies and GST-pull down assay revealed that SRPK1 bound to the region of sequential RS repeats (9–20) with affinity and recruited serine into the active site by a grab-and-pull manner. These results indicate SRPK1 may phosphorylate the p34cdc2 site in the N-terminal head of GV-lamin B3 at the RS motifs, which have the general property of aggregation.
SRPK1 was screened as a prominent lamin kinase candidate from goldfish ovary.
The goldfish lamin B3 (LB3) has RS repeats upstream of the cdc2 target site.
The RS repeats are conserved among fish LB3s but are not found in other lamins.
SRPK1 binds to the RS repeats with affinity and phosphorylates cdc2 site by a grab-and-pull manner.
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