title: Enhanced activity of human N-myristoyltransferase by dimethyl sulfoxide and related solvents in the presence of serine/threonine-containing peptide substrates.
abstract: Human N-myristoyltransferase (hNMT) activity was found to be stimulated several-fold by DMSO and its analogues in the presence of serine-containing peptide substrates. DMSO caused a concentration-dependent 10-fold stimulation of hNMT activity in the presence of a pp60(src)-derived peptide substrate (Gly-Ser-Ser-Lys-Ser-Lys-Pro-Lys-Arg). However, the stimulation of hNMT activity was not observed by DMSO when a cyclic AMP (cAMP)-dependent protein kinase-derived Ser-free peptide substrate (Gly-Asn-Ala-Ala-Ala-Ala-Lys-Lys-Arg-Arg) was used. These findings suggested that the effect of DMSO is on the substrate rather than on the enzyme. When a MARCKS (myristoylated alanine-rich C-kinase substrate)-derived peptide substrate (Gly-Ala-Gln-Phe-Ser-Lys-Thr-Ala-Arg-Arg) and the M2 gene segment of the reovirus type 3 peptide substrate (Gly-Asn-Ala-Ser-Ser-Ile-Lys-Lys-Lys) were used, hNMT activity was increased by approximately 8.5- and 7-fold, respectively. Dimethyl sulfone (20%) increased hNMT activity between 2.5- and 3.5-fold in the presence of pp60(src), MARCKS, and M2 gene segment peptides. Dimethyl formamide (20%) increased the hNMT activity by 8.5-, 8.5-, 5.5- and 3.5-fold when pp60(src), MARCKS, M2, and cAMP-dependent protein kinase-derived peptide substrates were used, respectively. Acetone (20%) also increased the hNMT activity by 20-fold in the presence of the pp60(src) peptide substrate. Dimethyl ammonium chloride (20%) caused about 6.5- and 2.5-fold increases in the hNMT activity in the presence of the pp60(src) and cAMP-dependent protein kinase-derived peptide substrates, respectively. Infrared spectroscopy showed a decreased intensity in the band at 3500-3600cm(-1) when the infrared spectrum of the pp60(src)-derived peptide was determined in the presence of DMSO. These results suggest the involvement of hydrogen bonding between the heteroatoms of the organic molecules and the hydrogen atoms of the free hydroxyl groups of the serine/threonine-containing peptide substrates. Such interactions appear to enhance the activity of hNMT towards its serine-containing substrates.
authors.affiliation: Health Research Division, Department of Pathology, College of Medicine, and Cancer Research Unit, Cancer Agency, University of Saskatchewan, 20 Campus Drive, Saskatoon, Saskatchewan, Canada S7N 4H4.
authors.forename: Mohammed Khysar
authors.initials: MK
authors.lastname: Pasha
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Dimmock
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
authors.forename: Rajendra K
authors.initials: RK
authors.lastname: Sharma
mesh_terms: D000217:Acyltransferases / Q000187:drug effects / Q000378:metabolism*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D010455:Peptides / Q000494:pharmacology; D012694:Serine / Q000737:chemistry; D012997:Solvents / Q000494:pharmacology; D013379:Substrate Specificity; D013912:Threonine / Q000737:chemistry
chemical_list: D010455:Peptides; D012997:Solvents; D013912:Threonine; D012694:Serine; D000217:Acyltransferases; C050480:glycylpeptide N-tetradecanoyltransferase; D004121:Dimethyl Sulfoxide