scholarly journals The Mitochondrial Genome Integrity Gene, MGI1, of Kluyveromyces lactis Encodes the β-Subunit of F1-ATPase

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1445-1454 ◽  
Author(s):  
Xin Jie Chen ◽  
G Desmond Clark-Walker
Keyword(s):  
Mitochondrial Genome ◽  
Kluyveromyces Lactis ◽  
Three Dimensional ◽  
Genome Integrity ◽  
Dimensional Structure ◽  
Deletion Mutants ◽  
Β Subunit ◽  
Gain Of Function ◽  
F1 Atpase ◽  
Γ Subunit

In a previous report, we found that mutations at the mitochondrial genome integrity locus, MGI1, can convert Kluyveromyces lactis into a petite-positive yeast. In this report, we describe the isolation of the MGI1 gene and show that it encodes the β-subunit of the mitochondrial F1-ATPase. The site of mutation in four independently isolated mgi1 alleles is at Arg435, which has changed to Gly in three cases and Ile in the fourth isolate. Disruption of MGI1 does not lead to the production of mitochondrial genome deletion mutants, indicating that an assembled F1 complex is needed for the “gain-of-function” phenotype found in mgi1 point mutants. The location of Arg435 in the β-subunit, as deduced from the three-dimensional structure of the bovine F1-ATPase, together with mutational sites in the previously identified mgi2 and mgi5 alleles, suggests that interaction of the β- and α- (MGI2) subunits with the γ-subunit (MGI5) is likely to be affected by the mutations.

Three-Dimensional Structure of F1-ATPase of Thermophilic Bacterium PS3 Obtained by Electron Crystallography

1993 ◽  
Vol 113 (2) ◽  
pp. 245-250 ◽  
Author(s):  
Noriyuki Ishii ◽  
Hideyuki Yoshimura ◽  
Kuniaki Nagayama ◽  
Yasuo Kagawa ◽  
Masasuke Yoshida
Keyword(s):  
Three Dimensional ◽  
Thermophilic Bacterium ◽  
Dimensional Structure ◽  
Electron Crystallography ◽  
Three Dimensional Structure ◽  
F1 Atpase

scholarly journals Novel insertion and deletion mutants of RpoB that render Mycobacterium smegmatis RNA polymerase resistant to rifampicin-mediated inhibition of transcription

Microbiology ◽  
2010 ◽  
Vol 156 (5) ◽  
pp. 1565-1573 ◽  
Author(s):  
Vidyasagar Malshetty ◽  
Krishna Kurthkoti ◽  
Arnab China ◽  
Bratati Mallick ◽  
Subburaj Yamunadevi ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Mycobacterium Smegmatis ◽  
Three Dimensional ◽  
Rna Polymerases ◽  
Dimensional Structure ◽  
Deletion Mutants ◽  
Insertion And Deletion ◽  
Calf Thymus ◽  
Specific Activities ◽  
Spatial Positioning

The startling increase in the occurrence of rifampicin (Rif) resistance in the clinical isolates of Mycobacterium tuberculosis worldwide is posing a serious concern to tuberculosis management. The majority of Rif resistance in bacteria arises from mutations in the RpoB subunit of the RNA polymerase. We isolated M. smegmatis strains harbouring either an insertion (6 aa) or a deletion (10 aa) in their RpoB proteins. Although these strains showed a compromised fitness for growth in 7H9 Middlebrook medium, their resistance to Rif was remarkably high. The attenuated growth of the strains correlated with decreased specific activities of the RNA polymerases from the mutants. While the RNA polymerases from the parent or a mutant strain (harbouring a frequently occurring mutation, H442Y, in RpoB) were susceptible to Rif-mediated inhibition of transcription from calf thymus DNA, those from the insertion and deletion mutants were essentially refractory to such inhibition. Three-dimensional structure modelling revealed that the RpoB amino acids that interact with Rif are either deleted or unable to interact with Rif due to their unsuitable spatial positioning in these mutants. We discuss possible uses of the RpoB mutants in studying transcriptional regulation in mycobacteria and as potential targets for drug design.

scholarly journals Mutation in the β subunit of F1 ATPase allows Kluyveromyces lactis to survive the disruption of  the KlPGS1 gene

2010 ◽  
Vol 10 (6) ◽  
pp. 727-734 ◽  
Author(s):  
Mária Patrás̆ová ◽  
Daniela Kos̆t'anová-Poliaková ◽  
Mária Šimočková ◽  
L'udmila Šabová
Keyword(s):  
Kluyveromyces Lactis ◽  
Β Subunit ◽  
F1 Atpase

The three-dimensional structure of rat liver mitochodria F1-ATPase: X-ray diffraction studies

1994 ◽  
Vol 1187 (2) ◽  
pp. 163-164 ◽  
Author(s):  
Mario Bianchet ◽  
Djamel Medjahed ◽  
Joanne Hulihen ◽  
Peter L. Pedersen ◽  
L.Mario Amzel
Keyword(s):  
Rat Liver ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Three Dimensional Structure ◽  
F1 Atpase

scholarly journals Mutations in MGI genes convert Kluyveromyces lactis into a petite-positive yeast.

Genetics ◽  
1993 ◽  
Vol 133 (3) ◽  
pp. 517-525 ◽  
Author(s):  
X J Chen ◽  
G D Clark-Walker
Keyword(s):  
Cytochrome C ◽  
Mitochondrial Genome ◽  
Ethidium Bromide ◽  
High Frequency ◽  
Kluyveromyces Lactis ◽  
Genome Integrity ◽  
Gene Products ◽  
Targeted Disruption ◽  
Nuclear Mutation ◽  
Petite Negative Yeast

Abstract Following targeted disruption of the unique CYC1 gene, the petite-negative yeast, Kluyveromyces lactis, was found to grow fermentatively in the absence of cytochrome c-mediated respiration. This observation encouraged us to seek mitochondrial mutants by treatment of K. lactis with ethidium bromide at the highest concentration permitting survival. By this technique, we isolated four mtDNA mutants, three lacking mtDNA and one with a deleted mitochondrial genome. In the three isolates lacking mtDNA, a nuclear mutation is present that permits petite formation. The three mutations occur at two different loci, designated MGI1 and MGI2 (for Mitochondrial Genome Integrity). The mgi mutations convert K. lactis into a petite-positive yeast. Like bakers' yeast, the mgi mutants spontaneously produce petites with deletions in mtDNA and lose this genome at high frequency on treatment with ethidium bromide. We suggest that the MGI gene products are required for maintaining the integrity of the mitochondrial genome and that, petite-positive yeasts may be naturally altered in one or other of these genes.

scholarly journals Structure and enzymatic mechanism of a moonlighting dUTPase

2013 ◽  
Vol 69 (12) ◽  
pp. 2298-2308 ◽  
Author(s):  
Ibolya Leveles ◽  
Veronika Németh ◽  
Judit E. Szabó ◽  
Veronika Harmat ◽  
Kinga Nyíri ◽  
...  
Keyword(s):  
Kinetic Data ◽  
Metal Ion ◽  
Three Dimensional ◽  
Genome Integrity ◽  
Dimensional Structure ◽  
Wild Type ◽  
Enzymatic Mechanism ◽  
Kinetics Studies ◽  
Inner Channel

Genome integrity requires well controlled cellular pools of nucleotides. dUTPases are responsible for regulating cellular dUTP levels and providing dUMP for dTTP biosynthesis. InStaphylococcus, phage dUTPases are also suggested to be involved in a moonlighting function regulating the expression of pathogenicity-island genes. Staphylococcal phage trimeric dUTPase sequences include a specific insertion that is not found in other organisms. Here, a 2.1 Å resolution three-dimensional structure of a φ11 phage dUTPase trimer with complete localization of the phage-specific insert, which folds into a small β-pleated mini-domain reaching out from the dUTPase core surface, is presented. The insert mini-domains jointly coordinate a single Mg2+ion per trimer at the entrance to the threefold inner channel. Structural results provide an explanation for the role of Asp95, which is suggested to have functional significance in the moonlighting activity, as the metal-ion-coordinating moiety potentially involved in correct positioning of the insert. Enzyme-kinetics studies of wild-type and mutant constructs show that the insert has no major role in dUTP binding or cleavage and provide a description of the elementary steps (fast binding of substrate and release of products). In conclusion, the structural and kinetic data allow insights into both the phage-specific characteristics and the generally conserved traits of φ11 phage dUTPase.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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