Disease relevance of ubiA

• The 92-min region of the Escherichia coli chromosome: location and cloning of the ubiA and alr genes [1].
• Mutations in aarE, the ubiA homolog of Providencia stuartii, result in high-level aminoglycoside resistance and reduced expression of the chromosomal aminoglycoside 2'-N-acetyltransferase [2].
• A ubiA mutant also exhibited thiol hypersensitivity [3].

High impact information on ubiA

• We now report that E. coli mutants defective in the hemA gene or in the ubiA-menA genes markedly accumulate the reduced form of DsbA during growth under the conditions of protoheme deprivation as well as ubiquinone/menaquinone deprivation [4].
• The sdgG suppressor is likely a mutation in one of three genes: ubiC, ubiA or yjbI [5].
• However, this strain had normal levels of 4-hydroxybenzoate octaprenyltransferase, the enzyme catalyzing the analogous prenylation reaction in ubiquinone biosynthesis, providing additional evidence that the two octaprenyltransferases are quite distinct [6].
• Neither IS16 nor the ubiA mutant strain could produce alkaline phosphatase (in contrast to their parent strains) after 2 h of induction, thus showing Dsb- phenotypes [3].
• Mutant complementation by plasmids showed that ubiA is located between malM and plsB [1].

Chemical compound and disease context of ubiA

• A ubiA- menA- double quinone mutant of Escherichia coli K12 was constructed together with other isogenic strains lacking either ubiquinone or menaquinone [7].
• Role of quinones in electron transport to oxygen and nitrate in Escherichia coli. Studies with a ubiA- menA- double quinone mutant [7].
• The ubiA gene from E. coli codes for 4-hydroxybenzoate: polyprenyldiphosphate 3-polyprenyltransferase, an integral membrane protein involved in ubiquinone biosynthesis [8].

Biological context of ubiA

• We have cloned the ubiCA gene cluster and determined the nucleotide sequence of ubiC and a portion of ubiA [9].
• The ubiA gene, coding for the 4-hydroxybenzoate octaprenyl transferase, was identified by sequence homology and complementation of a ubiA- strain [10].
• We have now manipulated the biosynthetic pathway leading to shikonin in L. erythrorhizon by introduction of the bacterial gene ubiA [11].
• However, an additional highly conserved region in the amino acid sequence of the ubiA enzyme could be detected, which also can be considered a putative (or rudimentary) active site [12].
• This site is characterized by a high sequence similarity to the aforementioned site and may give some hints regarding the evolutionary origin of the ubiA enzyme.Semiempirical quantum mechanical PM3 calculations have been performed to investigate the thermodynamics and kinetics of the catalysis mechanism [12].

Anatomical context of ubiA

• The prokaryotic ubiA gene was fused to two signal sequences for targeting of the resulting peptide to the endoplasmic reticulum (ER) [11].

Associations of ubiA with chemical compounds

• The growth rate and growth yield of the ubi+menA- strain was the same as the wild-type strain, whereas the ubiA-men+ strain grew more slowly on glucose, had a lower growth yield (30% of wild type) and accumulated relatively large quantities of acetate and lactate [7].
• This suggests that overexpression of ubiA alone is not sufficient to increase shikonin formation, and that further enzymes are involved in the regulation of this pathway [11].
• The respiration-defective phenotype of the ubiA mutant was complemented by expression of the COQ2 gene encoding the 4-hydroxy benzoate hexaprenyl transferase of Saccharomyces cerevisiae and such strains produced ubiquinone-8 [13].
• Strains with ubiA disrupted were constructed by chromosomal gene replacement with the chloramphenicol resistance gene [13].
• 4-Hydroxybenzoate is converted to 3-octaprenyl-4-hydroxybenzoate by 4-hydroxybenzoate octaprenyltransferase [9].

Analytical, diagnostic and therapeutic context of ubiA

• Genetic engineering on shikonin biosynthesis: expression of the bacterial ubiA gene in Lithospermum erythrorhizon [11].

References