title: Double mutant P96S/S120G of Nm23-H1 abrogates its NDPK activity and motility-suppressive ability.
abstract: The Nm23-H1 gene is a metastasis suppressor gene. However, its biochemical mechanism of suppressing the metastatic potential of cancer cells is still unknown. The previous hypothesis that a histidine protein kinase activity may contributes to the motility-suppressive effect of Nm23-H1 could not explain why the H118F mutant, a kinase-deficient mutant, still had motility-suppressive ability. We conducted a study on the double mutant P96S/S120G of Nm23-H1 and succeeded in introducing the RP-HPLC method in NDPK assay. The results showed that the double mutant P96S/S120G, when expressed in the bacteria, was completely aggregated in inclusion bodies; this mutant abrogated not only its motility-suppressive ability, but also its NDPK activity. Based on previous work and this study, we prompted that the deficiency of motility-suppressive function of S120G, P96S, and P96S/S120G mutants was due to their altered structure, which might deprive Nm23-H1 of most activities including kinase activity or interactions with other proteins.
authors.affiliation: Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, PR China. zhough1016@yahoo.com.cn
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zhou
authors.forename: Xueqin
authors.initials: X
authors.lastname: Yang
authors.forename: Daxing
authors.initials: D
authors.lastname: Zhu
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.forename: Wen
authors.initials: W
authors.lastname: Zhu
authors.forename: Zhilin
authors.initials: Z
authors.lastname: Sun
authors.forename: Qin
authors.initials: Q
authors.lastname: Yang
mesh_terms: D019943:Amino Acid Substitution; D002465:Cell Movement / Q000502:physiology*; D005998:Glycine / Q000235:genetics; D006801:Humans; D009154:Mutation; D054778:NM23 Nucleoside Diphosphate Kinases; D009701:Nucleoside-Diphosphate Kinase / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D011392:Proline / Q000235:genetics; D011994:Recombinant Proteins; D012694:Serine / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D054778:NM23 Nucleoside Diphosphate Kinases; D011994:Recombinant Proteins; D012694:Serine; D011392:Proline; C517938:NME1 protein, human; D009701:Nucleoside-Diphosphate Kinase; D005998:Glycine