title: Molecular characterization of the AdeI mutant of Chinese hamster ovary cells: a cellular model of adenylosuccinate lyase deficiency.
abstract: Adenylosuccinate lyase (ADSL, E. C. 4.3.2.2) carries out two non-sequential steps in de novo AMP synthesis, the conversion of succinylaminoimidazole carboxamide ribotide (SAICAR) to aminoimidazolecarboxamide ribotide (AICAR) and the conversion of succinyl AMP (AMPS) to AMP. In humans, mutations in ADSL lead to an inborn error of metabolism originally characterized by developmental delay, often with autistic features. There is no effective treatment for ADSL deficiency. Hypotheses regarding the pathogenesis include toxicity of high levels of SAICAR, AMPS, or their metabolites, deficiency of the de novo purine biosynthetic pathway, or lack of a completely functional purine cycle in muscle and brain. One important approach to understand ADSL deficiency is to develop cell culture models that allow investigation of the properties of ADSL mutants and the consequences of ADSL deficiency at the cellular level. We previously reported the isolation and initial characterization of mutants of Chinese hamster ovary (CHO-K1) cells (AdeI) that lack detectable ADSL activity, accumulate SAICAR and AMPS, and require adenine for growth. Here we report the cDNA sequences of ADSL from CHO-K1 and AdeI cells and describe a mutation resulting in an alanine to valine amino acid substitution at position 291 (A291V) in AdeI ADSL. This substitution lies in the "signature sequence" of ADSL, inactivates the enzyme, and validates AdeI as a cellular model of ADSL deficiency.
authors.affiliation: Eleanor Roosevelt Institute and Department of Biological Sciences, University of Denver, 2101 E. Wesley Avenue, Denver, CO 80208, USA.
authors.forename: Lydia K
authors.initials: LK
authors.lastname: Vliet
authors.forename: Terry G
authors.initials: TG
authors.lastname: Wilkinson
authors.forename: Nathan
authors.initials: N
authors.lastname: Duval
authors.forename: Guido
authors.initials: G
authors.lastname: Vacano
authors.forename: Christine
authors.initials: C
authors.lastname: Graham
authors.forename: Marie
authors.initials: M
authors.lastname: Zikánová
authors.forename: Vaclava
authors.initials: V
authors.lastname: Skopova
authors.forename: Veronika
authors.initials: V
authors.lastname: Baresova
authors.forename: Aleš
authors.initials: A
authors.lastname: Hnízda
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kmoch
authors.forename: David
authors.initials: D
authors.lastname: Patterson
mesh_terms: D000264:Adenylosuccinate Lyase / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D019943:Amino Acid Substitution; D000818:Animals; D001321:Autistic Disorder; D016466:CHO Cells; D020134:Catalytic Domain; D006224:Cricetinae; D003412:Cricetulus; D057075:Enzyme Assays; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D020836:Protein Structure, Quaternary; D011686:Purine-Pyrimidine Metabolism, Inborn Errors / Q000201:enzymology; D012333:RNA, Messenger / Q000737:chemistry; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D000264:Adenylosuccinate Lyase