SPL1-1, a Saccharomyces cerevisiae mutation affecting tRNA splicing

Kolman, Connie J.; Söll, Dieter

doi:10.1128/jb.175.5.1433-1442.1993

Cited by 49 publications

(36 citation statements)

References 46 publications

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“…Yeast NFS1 was first identified as a locus related to deleted tRNA splicing (therefore, its alternative name is SPL1) (17). We report here that the mitochondrial and extramitochondrial Fe/S protein maturation processes are involved in the 2-thio modification of cy-tRNA.…”

Section: Discussionmentioning

confidence: 70%

Thio Modification of Yeast Cytosolic tRNA Is an Iron-Sulfur Protein-Dependent Pathway

Nakai

Lill

et al. 2007

Molecular and Cellular Biology

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Defects in the yeast cysteine desulfurase Nfs1 cause a severe impairment in the 2-thio modification of uridine of mitochondrial tRNAs (mt-tRNAs) and cytosolic tRNAs (cy-tRNAs). Nfs1 can also provide the sulfur atoms of the iron-sulfur (Fe/S) clusters generated by the mitochondrial and cytosolic Fe/S cluster assembly machineries, termed ISC and CIA, respectively. Therefore, a key question remains as to whether the biosynthesis of Fe/S clusters is a prerequisite for the 2-thio modification of the tRNAs in both of the subcellular compartments of yeast cells. To elucidate this question, we asked whether mitochondrial ISC and/or cytosolic CIA components besides Nfs1 were involved in the 2-thio modification of these tRNAs. We demonstrate here that the three CIA components, Cfd1, Nbp35, and Cia1, are required for the 2-thio modification of cy-tRNAs but not of mt-tRNAs. Interestingly, the mitochondrial scaffold proteins Isu1 and Isu2 are required for the 2-thio modification of the cy-tRNAs but not of the mt-tRNAs, while mitochondrial Nfs1 is required for both 2-thio modifications. These results clearly indicate that the 2-thio modification of cy-tRNAs is Fe/S protein dependent and thus requires both CIA and ISC machineries but that of mt-tRNAs is Fe/S cluster independent and does not require key mitochondrial ISC components except for Nfs1.

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Section: Discussionmentioning

confidence: 70%

Thio Modification of Yeast Cytosolic tRNA Is an Iron-Sulfur Protein-Dependent Pathway

Nakai

Lill

et al. 2007

Molecular and Cellular Biology

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“…As in B. subtilis, the flanking regions of the yeast niqS-like gene share no homology with the nif genes that flank nifS in nitrogen-fixing bacteria. The yeast nifS-like gene is thought to be involved in both tRNA processing (15) and mitochondrial metabolism, and disruption of this gene is lethal (24). The existence of nifS-like genes in nitrogen-fixing bacteria, as well as in B. subtilis, L. bulgaricus, and S. cerevisiae (none of which fix nitrogen), suggests that the functions of nifS gene products, presumably the formation of Fe-S clusters in enzymes, have been conserved throughout evolution, although the target polypeptides may vary between different organisms.…”

Section: Discussionmentioning

confidence: 99%

Cloning, nucleotide sequence, and regulation of the Bacillus subtilis nadB gene and a nifS-like gene, both of which are essential for NAD biosynthesis

Sun

Setlow

1993

J Bacteriol

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NAD plays an important role in cellular metabolism, as it functions as a cofactor in numerous oxidation-reduction reactions. NAD is synthesized from quinolinic acid (Qa) via a pathway which is similar in all organisms which have been examined (Fig. 1). On the other hand, the pathway for Qa formation differs in different organisms (7). In Escherichia coli and Salmonella typhimurium, as well as in many other eubacteria, Qa is synthesized from L-aspartate and dihydroxyacetone phosphate by a Qa synthetase complex (7,33). This complex consists of two enzymes, L-aspartate oxidase and Qa synthetase A. Aspartate oxidase catalyzes oxidation of L-aspartate to iminoaspartate, which is subsequently condensed with dihydroxyacetone phosphate by Qa synthetase A to form Qa (Fig. 1). In E. coli, the latter two enzymes are encoded by the unlinked genes nadB and nadA4, respectively, both of which have been cloned and sequenced (6). Qa is then converted to nicotinic acid mononucleotide (NaMN) by Qa phosphoribosyltransferase, which is coded for by the nadC gene (23). NaMN then reacts with ATP in a reaction catalyzed by the nadD gene product to give nicotinic acid adenine dinucleotide, which is then amidated by the nadE gene product to form NAD. Cells can also convert exogenous nicotinic acid (Nic) to NaMN by Nic phosphoribosyltransferase. When either nadA, nadB, or nadC is inactivated, cells become dependent on Nic for growth.The NAD biosynthetic pathway in Bacillus subtilis has been thought to be the same as in E. coli (7), although the regulation of some of the B. subtilis enzymes, for example, Qa phosphoribosyltransferase, may be rather different than in E. coli (28). Nic-requiring auxotrophic mutants have been isolated in B. subtilis, and the mutations (termed nic) were mapped near the spoOB-pheBA region (2,10,13 The chromosomal DNA library was used to transform strain PS1589 to chloramphenicol resistance. Strain PS1589 carries the divIVB1 mutation, which is known to be closely linked to the site of nic mutations (16,26). Several different Cmr transformants were found to have the cat gene closely linked to divIVB1. Three-factor crosses showed that in one of the Cmr transformants, strain PS1591, the order of markers was divIVB-spoOB-cat.

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“…The NFS1 gene has been shown to be essential for cell viability (5,8). Therefore, a yeast strain named YN101 in which the chromosomal NFS1 gene was expressed under the control of the GAL1 promoter was constructed and used as a host strain for in vivo complementation analyses.…”

Section: Mutation Of the Nls Sequence In Nfs1p Induced A Growth Defecmentioning

confidence: 99%

Nuclear Localization of Yeast Nfs1p Is Required for Cell Survival

Nakai

Hayashi

et al. 2001

Journal of Biological Chemistry

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Saccharomyces cerevisiae Nfs1p is mainly found in the mitochondrial matrix and has been shown to participate in iron-sulfur cluster assembly. We show here that Nfs1p contains a potential nuclear localization signal, RRRPR, in its mature part. When this sequence was mutated to RRGSR, the mutant protein could not restore cell growth under chromosomal NFS1-depleted conditions. However, this mutation did not affect the function of Nfs1p in biogenesis of mitochondrial iron-sulfur proteins. The growth defect of the mutant was complemented by simultaneous expression of the mature Nfs1p, which contains the intact nuclear localization signal but lacks its mitochondrial-targeting presequence. These results suggest that a fraction of Nfs1p is localized in the nucleus and is essential for cell viability.The NifS protein is found in various organisms and is involved in iron-sulfur protein biosynthesis. In the diazotroph Azotobacter vinelandii, the nifS gene was first identified as a member of the nif operon that plays an essential role in the biosynthesis of nitrogenase (1). Extensive biochemical analyses of A. vinelandii NifS reveal that it is a PLP 1 -containing enzyme exhibiting desulfurase activity that produces elemental sulfur and L-alanine from L-cysteine (2). These findings suggest that the physiological function of NifS is to supply inorganic sulfur for the assembly of the iron-sulfur cluster in nitrogenase (3, 4).Many eukaryotic NifS homologues have been identified, of which the Saccharomyces cerevisiae NifS homologue, Nfs1p, is the best characterized (5-9). The nfs1 null mutant is lethal (5, 9), and Nfs1p is localized mostly to the mitochondrial matrix (7-9). Mitochondrial Nfs1p mediates the assembly of the ironsulfur cluster of both mitochondrial and cytosolic iron-sulfur proteins (6, 8) and also regulates mitochondrial and cytosolic iron homeostasis (9). Kolman and Söll (5) also show that a mutation in the NFS1 gene suppressed a certain tRNA-splicing mutant (5), although the role of Nfs1p in the process of tRNA splicing, which is thought to take place in the nucleus, remains unclear.Mouse and human counterparts to Nfs1p (mNfs1 and hNfs1, respectively) have also been identified (7, 10). We showed that mNfs1 was found mainly in the mitochondrial matrix (7). The full-length hNfs1 protein also possesses a mitochondrial-targeting presequence and has been shown to be localized to mitochondria. Different sized hNfs1 proteins from a single transcript have also been detected in the cytosolic and nuclear fractions (10), but the physiological significance of these extramitochondrial hNfs1 proteins has not been elucidated.The Escherichia coli NifS homologue, IscS, is a multi-functional enzyme that possesses important physiological functions not only in iron-sulfur cluster assembly (11, 12) but also in sulfur transfer to some intracellular compounds (13-18). These results suggest that a fraction of Nfs1p may have some essential function other than iron-sulfur cluster assembly, possibly in a different subcellular location. In...

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SPL1-1, a Saccharomyces cerevisiae mutation affecting tRNA splicing

Cited by 49 publications

References 46 publications

Thio Modification of Yeast Cytosolic tRNA Is an Iron-Sulfur Protein-Dependent Pathway

Thio Modification of Yeast Cytosolic tRNA Is an Iron-Sulfur Protein-Dependent Pathway

Cloning, nucleotide sequence, and regulation of the Bacillus subtilis nadB gene and a nifS-like gene, both of which are essential for NAD biosynthesis

Nuclear Localization of Yeast Nfs1p Is Required for Cell Survival

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