Pollack J Dennis, Myers Melissa A, Dandekar Thomas, Herrmann Richard
Department of Molecular Virology, Immunology, and Medical Genetics, The College of Medicine and Public Health, The Ohio State University, Columbus, Ohio 43210, USA.
OMICS. 2002;6(3):247-58. doi: 10.1089/15362310260256909.
The small genome Mollicutes whose DNAs are completely sequenced (Mycoplasma genitalium, Mycoplasma pneumoniae, Mycoplasma pulmonis, and Ureaplasma urealyticum [parvum]) lack a gene (ndk) for the presumably essential nucleoside diphosphate kinase (NDPK). We hypothesized that other activities might replace NDPK activity. We found in M. genitalium G37(T), Mycoplasma pneumoniae FH(T), Mycoplasma fermentans PG18(T), and Mycoplasma capricolum subsp. capricolum Kid(T) that their 6-phosphofructokinases (6-PFKs), phosphoglycerate kinases (PGKs), pyruvate kinases (PKs), and acetate kinases (AKs), besides reactant ADP/ATP, could use other ribo- and deoxyribo-purine and pyrimidine NDPs and NTPs. These activities could compensate for the absence of an orthologous ndk gene in the Mycoplasmataceae. They suggest a metabolically varied and consequential role for unrelated and perhaps unsuspected "replacement" or compensatory enzymes that may confound metabolic prediction. We partially purified and biochemically characterized the PKs, 6-PFKs, PGKs, and AKs from M. capricolum subsp. capricolum Kid(T) and M. fermentans PG18(T).
基因组较小的柔膜菌纲细菌，其DNA已被完全测序（生殖支原体、肺炎支原体、肺支原体和解脲脲原体[微小脲原体]），缺乏一个可能是必需的核苷二磷酸激酶（NDPK）基因（ndk）。我们推测其他活性可能会取代NDPK活性。我们在生殖支原体G37(T)、肺炎支原体FH(T)、发酵支原体PG18(T)和山羊支原体山羊亚种Kid(T)中发现，它们的6-磷酸果糖激酶（6-PFK）、磷酸甘油酸激酶（PGK）、丙酮酸激酶（PK）和乙酸激酶（AK），除了反应物ADP/ATP外，还可以使用其他核糖和脱氧核糖嘌呤及嘧啶核苷二磷酸和核苷三磷酸。这些活性可以弥补支原体科中直系同源ndk基因的缺失。它们表明，对于可能混淆代谢预测的不相关且可能未被怀疑的“替代”或补偿性酶，其在代谢方面具有多样且重要的作用。我们从山羊支原体山羊亚种Kid(T)和发酵支原体PG18(T)中部分纯化并对PK、6-PFK、PGK和AK进行了生化特性分析。
