Swartz Carol D, Parks Nick, Umbach David M, Ward William O, Schaaper Roel M, DeMarini David M
Department of Environmental Science and Engineering, University of North Carolina, Chapel Hill, North Carolina, USA.
Environ Mol Mutagen. 2007 Oct;48(8):694-705. doi: 10.1002/em.20343.
The standard Salmonella mutagenicity (Ames) tester strains are missing 15-119 genes due to the extended Delta(gal-bio-uvrB) mutations that render the strains excision-repair deficient (DeltauvrB). We constructed strains of Salmonella that are homologous to tester strains TA98 and TA100 except that in place of the uvrB deletion, they contain single-gene defects in either uvrB, moaA, moeA, or both uvrB and moeA. We then tested the following mutagens in these strains: 2-acetylaminofluorene, Glu-P-1, 4-aminobiphenyl, benzo[a]pyrene, MX, 1-nitropyrene, 6-hydroxylaminopurine (HAP), and 2-amino-6-hydroxylaminopurine (AHAP). We confirmed in Salmonella a previous finding in Escherichia coli that the enhanced mutagenicity of the purine analogues HAP and AHAP is not due to the deletion of the uvrB gene but due to the deletion of moeA and/or moaA, which are involved in molybdenum cofactor biosynthesis. The spontaneous mutant frequency and induced mutagenic potency of mutagens due to the extended DeltauvrB mutation are due largely to the deletion of uvrB and to some extent of moeA/moaA at the frameshift hisD3052 allele of TA98 but involve other genes in addition to uvrB and moeA/moaA at the base-substitution hisG46 allele of TA100. The extended DeltauvrB mutation does not prevent the detection of mutagens that would have been detected in a strain containing a single uvrB defect. Because of the deletion of moeA/moaA, the extended uvrB deletion generally enhanced spontaneous and induced mutagenicity, especially at the base-substitution allele. This enhanced sensitivity may underlay the severe health effects in humans who have mutations in molybdenum cofactor biosynthesis genes.
标准沙门氏菌致突变性(艾姆斯)测试菌株由于存在扩展的Δ(gal - bio - uvrB)突变而缺失15 - 119个基因,这些突变使菌株缺乏切除修复能力(ΔuvrB)。我们构建了与测试菌株TA98和TA100同源的沙门氏菌菌株,不同之处在于,它们不是缺失uvrB,而是在uvrB、moaA、moeA中存在单基因缺陷,或者在uvrB和moeA两者中存在单基因缺陷。然后我们在这些菌株中测试了以下诱变剂:2 - 乙酰氨基芴、Glu - P - 1、4 - 氨基联苯、苯并[a]芘、MX、1 - 硝基芘、6 - 羟基氨基嘌呤(HAP)和2 - 氨基 - 6 - 羟基氨基嘌呤(AHAP)。我们在沙门氏菌中证实了先前在大肠杆菌中的一项发现,即嘌呤类似物HAP和AHAP诱变活性增强并非由于uvrB基因缺失,而是由于参与钼辅因子生物合成的moeA和/或moaA基因缺失。由于扩展的ΔuvrB突变导致的诱变剂自发突变频率和诱导诱变效力在很大程度上归因于uvrB缺失,在TA98的移码hisD3052等位基因处,在一定程度上也归因于moeA/moaA缺失,但在TA100的碱基替换hisG46等位基因处,除uvrB和moeA/moaA外还涉及其他基因。扩展的ΔuvrB突变并不妨碍检测在含有单个uvrB缺陷的菌株中本可检测到的诱变剂。由于moeA/moaA缺失,扩展的uvrB缺失通常会增强自发和诱导的诱变活性,尤其是在碱基替换等位基因处。这种增强的敏感性可能是钼辅因子生物合成基因突变的人类出现严重健康问题的原因。