A
            <i>Saccharomyces cerevisiae</i>
            Mutant Defective in Saturated Fatty Acid Biosynthesis

Schweizer, Eckhart; Bolling, H.

doi:10.1073/pnas.67.2.660

Cited by 81 publications

(40 citation statements)

References 18 publications

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“…Radioisotope incorporation was measured: 5 ml of exponentially growing culture ['4C]acetate by the mutants to obtain instantaneous rates of total lipid synthesis in both fatty-acid-supplemented and unsupplemented cultures. To perform these measurements, we returned to conditions (leucine supplementation) favoring the nearly exclusive incorporation of [ (17,18) and Neurospora crassa (19) …”

Section: Methodsmentioning

confidence: 99%

Temperature-Sensitive Mutants of Escherichia coli Requiring Saturated and Unsaturated Fatty Acids for Growth: Isolation and Properties

Harder

Beacham

Cronan

et al. 1972

Proc. Natl. Acad. Sci. U.S.A.

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A procedure is described for selection of temperature-sensitive mutants affecting fatty-acid synthesis based upon radiation suicide of wild-type organisms by tritiated acetate selectively incorporated into fatty acids. At 370, two of the mutants extensively incorporate fatty-acid supplements provided in the medium, and grow for extended periods only when a trans-unsaturated or a combination of saturated and cis-unsaturated fatty acids is available. In vivo fatty-acid synthesis, measured by ['4Cjacetate incorporation, is temperature-sensitive in these strains relative to protein synthesis and other nonlipid macromolecular syntheses using acetate. The biochemical nature of these mutations has not been identified.Saturated, unsaturated, and ,3-hydroxy fatty acids of Escherichia coli are synthesized in part by a common pathway. From the known sequence of reactions, one might expect to isolate mutants blocked in total fatty-acid synthesis or selectively defective in the synthesis of one or more classes of fatty acid. Unsaturated fatty-acid auxotrophs have been isolated by exogenous replacement of the essential fatty acid and penicillin enrichment (1-3). Recovery of such mutants is low, because under conditions of fatty-acid starvation (used in penicillin enrichment) the unsaturated fatty-acid auxotrophs continue to grow for one generation, and then begin to die (2). Furthermore, this approach, which relies on replacement, has not yielded any other class of fatty-acid biosynthetic (fab) mutants. Mutations affecting the synthesis of these other types of fatty acids may not be critical to cells or, on the other hand, might be lethal. For either reason they would not ordinarily be isolated. Recently, conditional mutants for phospholipid biosynthesis were isolated because they failed to assimilate a radioactive, and specific, phospholipid precursor and, thus, were protected from radiation death undergone by cells with an intact biosynthetic pathway (4). In this paper, we report conditions for selectively labeling cellular fatty acids with tritiated acetate of high specific activity and isolating,'conditional mutants affecting fatty-acid synthesis. Such mutants survive better than wild-type cells because they do not concentrate the radioisotope. Properties of two of these mutants are described. MATERIALS AND METHODSStrains and Media. All bacterial strains were K-12 strains of E. coli. The mutants obtained in this study were derived from AB1623, a glutamate-requiring strain defective in citrate synthetase, which was provided by Dr. H. L. Kornberg and has been described (5). LA1-6 and LA2-22 are two independently isolated mutants thermosensitive for fatty-acid biosynthesis; LA1-6-2 and LA2-22-6 are wild-type transductants of these mutants. In the symbols adopted for classifying mutants, L indicates lipid, A identifies the genetic background (AB1623), the numeral before the hyphen refers to the particular mutant selection, and the number after the hyphen is the particular isolate obtained. C600 is F-and requires leuci...

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Section: Methodsmentioning

confidence: 99%

Temperature-Sensitive Mutants of Escherichia coli Requiring Saturated and Unsaturated Fatty Acids for Growth: Isolation and Properties

Harder

Beacham

Cronan

et al. 1972

Proc. Natl. Acad. Sci. U.S.A.

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“…Myristoyl-CoA represents ϳ5% of its acyl-CoA products (44,45). Fas1p mRNA encodes the ␤-subunit of the ␣ 6 ␤ 6 Fas complex.…”

Section: Post-diauxic Phase and Is Not Induced In Nmt1-451dfaa4⌬mentioning

confidence: 99%

A Role for Saccharomyces cerevisiae Fatty Acid Activation Protein 4 in Regulating ProteinN-Myristoylation during Entry into Stationary Phase

Ashrafi

Farazi

Gordon

1998

Journal of Biological Chemistry

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“…Sixty-one are alleles of acc1 (55, 67), while others bear mutations in fatty acid synthase (19,73,74) or in the enzyme which is necessary for producing active Acc1p, biotin: apo-Acc1p ligase (Acc2p [55]). …”

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confidence: 99%

A Yeast Acetyl Coenzyme A Carboxylase Mutant Links Very-Long-Chain Fatty Acid Synthesis to the Structure and Function of the Nuclear Membrane-Pore Complex

Schneiter

Hitomi

Ivessa

et al. 1996

Molecular and Cellular Biology

183

185

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The conditional mRNA transport mutant of Saccharomyces cerevisiae, acc1-7-1 (mtr7-1), displays a unique alteration of the nuclear envelope. Unlike nucleoporin mutants and other RNA transport mutants, the intermembrane space expands, protuberances extend from the inner membrane into the intermembrane space, and vesicles accumulate in the intermembrane space. MTR7 is the same gene as ACC1, encoding acetyl coenzyme A (CoA) carboxylase (Acc1p), the rate-limiting enzyme of de novo fatty acid synthesis. Genetic and biochemical analyses of fatty acid synthesis mutants and acc1-7-1 indicate that the continued synthesis of malonyl-CoA, the enzymatic product of acetyl-CoA carboxylase, is required for an essential pathway which is independent from de novo synthesis of fatty acids. We provide evidence that synthesis of very-long-chain fatty acids (C 26 atoms) is inhibited in acc1-7-1, suggesting that very-long-chain fatty acid synthesis is required to maintain a functional nuclear envelope.The regulation of synthesis and transport of phospholipids has been characterized at length, but the signals which determine the phospholipid and fatty acid composition of particular membranes and membrane-specific lipid requirements are not well understood (7,62,81,83). The present investigation, which is the outgrowth of analysis of a yeast (Saccharomyces cerevisiae) mutant which accumulates poly(A) ϩ RNA in the nucleus at the restrictive temperature (41), documents a critical relationship between fatty acid chain length and the integrity of the nuclear membrane and nuclear pore complex (NPC).The biosynthesis of very-long-chain fatty acids requires four enzyme systems: acetyl coenzyme A (CoA) carboxylase, fatty acid synthase, fatty acid desaturase, and the fatty acyl chain elongation system (Fig. 1). The rate-limiting step of the de novo synthesis of fatty acids is under control of the first of these, acetyl-CoA carboxylase (Acc1p; EC 6.4.1.2). This biotinylated enzyme catalyzes the ATP-dependent carboxylation of acetyl-CoA to yield malonyl-CoA, which serves as the twocarbon-unit donor for the subsequent synthesis of long-chain fatty acids by the fatty acid synthase complex. The chain length of newly synthesized fatty acids appears to depend on the concentration of malonyl-CoA rather than on the activity of the fatty acid synthase complex (35, 43a, 82). Acc1p thus regulates both the overall rate of de novo synthesis and chainlength distribution of long-chain fatty acids. It is perhaps for this reason that its activity is subject to complex regulation (48). Yeast Acc1p/Fas3p has a subunit molecular mass of 250 kDa, is active as a tetramer, and is subject to short-term regulation by phosphorylation (2, 60, 90). Its transcription is positively regulated by Ino2p and Ino4p and negatively regulated by Opi1p; i.e., it is under the general control of phospholipid synthesis (14, 31).Many yeast long-chain fatty acid auxotrophs have been isolated (72). Sixty-one are alleles of acc1 (55, 67), while others bear mutations in fatty acid synthase (19,...

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A Saccharomyces cerevisiae Mutant Defective in Saturated Fatty Acid Biosynthesis

Cited by 81 publications

References 18 publications

Temperature-Sensitive Mutants of Escherichia coli Requiring Saturated and Unsaturated Fatty Acids for Growth: Isolation and Properties

Temperature-Sensitive Mutants of Escherichia coli Requiring Saturated and Unsaturated Fatty Acids for Growth: Isolation and Properties

A Role for Saccharomyces cerevisiae Fatty Acid Activation Protein 4 in Regulating ProteinN-Myristoylation during Entry into Stationary Phase

A Yeast Acetyl Coenzyme A Carboxylase Mutant Links Very-Long-Chain Fatty Acid Synthesis to the Structure and Function of the Nuclear Membrane-Pore Complex

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