title: The SAM domain of the RhoGAP DLC1 binds EF1A1 to regulate cell migration.
abstract: Deleted in liver cancer 1 (DLC1) is a multi-modular Rho-GTPase-activating protein (RhoGAP) and a tumor suppressor. Besides its RhoGAP domain, functions of other domains in DLC1 remain largely unknown. By protein precipitation and mass spectrometry, we identified eukaryotic elongation factor 1A1 (EF1A1) as a novel partner for the sterile alpha motif (SAM) domain of DLC1 but not the SAM domain of DLC2. The solution structure of DLC1 SAM revealed a new monomeric fold with four parallel helices, similar to that of DLC2 SAM but distinct from other SAM domains. Mutating F38, L39 and F40 within a hydrophobic patch retained its overall structure but abolished its interaction with EF1A1 with F38 and L39 forming an indispensable interacting motif. DLC1 SAM did not localize to and was not required for DLC1 to suppress the turnover of focal adhesions. Instead, DLC1 SAM facilitated EF1A1 distribution to the membrane periphery and ruffles upon growth factor stimulation. Compared with wild-type DLC1, the non-interactive DLC1 mutant is less potent in suppressing cell migration, whereas overexpression of the DLC1 SAM domain alone, but not the non-interactive mutant SAM or DLC2 SAM, greatly enhanced cell migration. This finding reveals a novel contribution of the SAM-EF1A1 interaction as a potentially important GAP-independent modulation of cell migration by DLC1.
authors.affiliation: Cell Signaling and Developmental Biology Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhong
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Zhang
authors.forename: Shuai
authors.initials: S
authors.lastname: Yang
authors.forename: Unice J K
authors.initials: UJ
authors.lastname: Soh
authors.forename: Jan Paul
authors.initials: JP
authors.lastname: Buschdorf
authors.forename: Yi Ting
authors.initials: YT
authors.lastname: Zhou
authors.forename: Daiwen
authors.initials: D
authors.lastname: Yang
authors.forename: Boon Chuan
authors.initials: BC
authors.lastname: Low
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D020690:GTPase-Activating Proteins; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D020648:Peptide Elongation Factor 1 / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D051381:Rats; D016415:Sequence Alignment; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C112352:DLC1 protein, human; C094814:EEF1A1 protein, human; D020690:GTPase-Activating Proteins; D020648:Peptide Elongation Factor 1; D025521:Tumor Suppressor Proteins