Singer M E, Finnerty W R
J Bacteriol. 1985 Dec;164(3):1011-6. doi: 10.1128/jb.164.3.1011-1016.1985.
The role of fatty aldehyde dehydrogenases (FALDHs) in hexadecane and hexadecanol metabolism was studied in Acinetobacter sp. strain HO1-N. Two distinct FALDHs were demonstrated in Acinetobacter sp. strain HO1-N: a membrane-bound, NADP-dependent FALDH activity induced 5-, 15-, and 9-fold by growth on hexadecanol, dodecyl aldehyde, and hexadecane, respectively, and a constitutive, NAD-dependent, membrane-localized FALDH. The NADP-dependent FALDH exhibited apparent Km and Vmax values for decyl aldehyde of 5.0, 13.0, 18.0, and 18.3 microM and 537.0, 500.0, 25.0, and 38.0 nmol/min in hexadecane-, hexadecanol-, ethanol-, palmitate-grown cells, respectively. FALDH isozymes ald-a, ald-b, and ald-c were demonstrated by gel electrophoresis in extracts of hexadecane- and hexadecanol-grown cells. ald-a, ald-b, and ald-d were present in dodecyl aldehyde-grown cells, while palmitate-grown control cells contained ald-b and ald-d. Dodecyl aldehyde-negative mutants were isolated and grouped into two phenotypic classes based on growth: class 1 mutants were hexadecane and hexadecanol negative and class 2 mutants were hexadecane and hexadecanol positive. Specific activity of NADP-dependent FALDH in Ald21 (class 1 mutant) was 85% lower than that of wild-type FALDH, while the specific activity of Ald24 (class 2 mutant) was 55% greater than that of wild-type FALDH. Ald21R, a dodecyl aldehyde-positive revertant able to grow on hexadecane, hexadecanol, and dodecyl aldehyde, exhibited a 100% increase in the specific activity of the NADP-dependent FALDH. The oxidation of [3H]hexadecane byAld21 yielded the accumulation of 61% more fatty aldehyde than the wild type, while Ald24 accumulated 27% more fatty aldehyde, 95% more fatty alcohol, and 65% more wax ester than the wild type. This study provides genetic and physiological evidence for the role of fatty aldehyde as an essential metabolic intermediate and NADP-dependent FALDH as a key enzyme in the dissimilation of hexadecane, hexadecanol, and dodecyl aldehyde in Acinetobactor sp. strain HO1-N.
在不动杆菌属HO1 - N菌株中研究了脂肪醛脱氢酶（FALDHs）在十六烷和十六醇代谢中的作用。在不动杆菌属HO1 - N菌株中证实了两种不同的FALDHs：一种是膜结合的、依赖NADP的FALDH活性，分别在以十六醇、十二烷基醛和十六烷为生长底物时诱导5倍、15倍和9倍，另一种是组成型的、依赖NAD的、定位于膜的FALDH。依赖NADP的FALDH对癸醛的表观Km和Vmax值在以十六烷、十六醇、乙醇、棕榈酸生长的细胞中分别为5.0、13.0、18.0和18.3 microM以及537.0、500.0、25.0和38.0 nmol/min。通过凝胶电泳在以十六烷和十六醇生长的细胞提取物中证实了FALDH同工酶ald - a、ald - b和ald - c。ald - a、ald - b和ald - d存在于以十二烷基醛生长的细胞中，而以棕榈酸生长的对照细胞含有ald - b和ald - d。分离出十二烷基醛阴性突变体，并根据生长情况将其分为两个表型类别：第1类突变体对十六烷和十六醇呈阴性，第2类突变体对十六烷和十六醇呈阳性。Ald21（第1类突变体）中依赖NADP的FALDH的比活性比野生型FALDH低85%，而Ald24（第2类突变体）的比活性比野生型FALDH高55%。Ald21R是一种能够在十六烷、十六醇和十二烷基醛上生长的十二烷基醛阳性回复突变体，其依赖NADP的FALDH的比活性增加了100%。与野生型相比，Ald21氧化[3H]十六烷产生的脂肪醛积累量多61%，而Ald24积累的脂肪醛多27%，脂肪醇多95%，蜡酯多65%。本研究为脂肪醛作为必需代谢中间体以及依赖NADP的FALDH作为不动杆菌属HO1 - N菌株中十六烷、十六醇和十二烷基醛异化作用中的关键酶的作用提供了遗传和生理学证据。
