Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
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The trematode, Fasciola hepatica, and the cestode, Spirometra mansonoides have been shown to be similar to the nematode Ascaris lumbricoides in that all three decarboxylate succinate to propionate plus CO2. Associated with this decarboxylation is an incorporation of 32Pi into organic phosphate. Both the decarboxylation and phosphorylation are markedly stimulated by the addition of propionyl-CoA, are dependent on coenzyme B12 and are inhibited by avidin. The trematode and cestode exhibit propionyl-CoA carboxylase, methylmalonyl-CoA mutase and acyl-CoA transferase activities in sonicated mitochondrial preparations. Data are consistent with the occurrence of a mitochondrial substrate level site for ATP generation which is coupled with the decarboxylation of succinate. In Fasciola preparations, acetyl-CoA stimulates the decarboxylation and phosphorylation to a considerably larger extent than propionyl-CoA, indicating the possibility that acetyl-CoA may serve physiologically in these reactions by donating the CoA moiety to succinate.
Mol Biochem Parasitol 1981 May
PMID:Succinate decarboxylation to propionate and the associated phosphorylation in Fasciola hepatica and Spirometra mansonoides. 611 29

Propionic acidemia results from deficiency of propionyl-CoA carboxylase (PCC) activity. PCC is a biotin-dependent, mitochondrial enzyme composed of alpha- and beta-subunits (structure, alpha 4 beta 4), with the alpha-subunit containing the biotin ligand. About two-thirds of fibroblast lines from patients with mutations in the PCCB (beta-subunit) gene show interallelic complementation in cell fusion experiments (the pccB and pccC subgroups of the pccBC major group defining beta-subunit mutations, where pccB x pccC fusions show complementation). We previously identified the mutations in several pccB or pccC cell lines and suggested that point mutations or small, in-frame insertions or deletions were likely responsible for the complementation obtained between beta-subunit defects. To test this hypothesis, we have introduced five different mutations (three pccB and two pccC) that fit these criteria into a PCC beta-subunit cDNA plasmid expressed from a cytomegalovirus promoter. The cDNA plasmids were microinjected into mutant fibroblasts and the cells were assayed by radioautographic detection of 14C-propionate incorporation into cellular macromolecules. Four different mutations (Pro228Leu or dupKICK140 from pccB or delta IIe408 or Arg410Trp from pccC) complemented cells from complementation subgroups in a pattern congruent with the results obtained in cell fusion experiments. The fifth mutation, Arg536Asn, which was found both in a complementing pccB and a non-complementing pccBC cell line, failed to complement any of the mutant cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)
Hum Mol Genet 1995 Jun
PMID:Interallelic complementation of beta-subunit defects in fibroblasts of patients with propionyl-CoA carboxylase deficiency microinjected with mutant cDNA constructs. 765 56

Using an oligonucleotide corresponding to the consensus sequence for the biotin-binding motif, two unlinked genetic loci, bpl1 and bpl2, were cloned from the erythromycin producer Saccharopolyspora erythraea and the nucleotide sequences of a c. 4 kb segment from each determined. The two loci share a virtually identical segment of 1746 nucleotides, coinciding with most of the genes designated bcpA1 and bcpA2 present in bpl1 and bpl2, respectively. The deduced sequences of these genes are highly similar to that of the alpha-chain of mammalian propionyl-CoA carboxylase. Upstream of bcpA2 lies pccB, the gene encoding the beta-chain of this enzyme. Mutant strains carrying frameshift mutations in bcpA1 and pccB were constructed, but we failed to isolate insertional mutants in bcpA2. Propionyl-CoA carboxylase activity was undetectable in the pccB mutant, but was unaffected in the bcpA1-defective strain. These results indicate that pccB encodes the beta-chain of propionyl-CoA carboxylases, and suggest that the alpha-chain of this enzyme, which is likely to be encoded by bcpA2, is shared with some other essential biotin-dependent enzyme. The pccB mutation had no impact on erythromycin production in complex medium.
Mol Microbiol 1996 Mar
PMID:Erythromycin production in Saccharopolyspora erythraea does not require a functional propionyl-CoA carboxylase. 883 Feb 78

We developed a bacterial expression system for the human alpha and beta cDNAs of propionyl-CoA carboxylase (PCC). These cDNAs (less the putative mitochondrial matrix targeting presequences) were co-expressed in Escherichia coli on one plasmid vector with each cDNA having its own IPTG-inducible promoter. Only negligible amounts of active PCC were measured despite the presence of both alpha and beta subunits as indicated by Western blot analysis and the almost complete biotinylation of the alpha subunit. Co-expression of this plasmid with a second plasmid vector over-expressing the E. coli chaperonin proteins, groES and groEL, resulted in a several hundred-fold increase in PCC specific activity, to a level comparable with that found in crude human liver extracts. PCC was partially purified on monomeric avidin affinity resin and the presence of both alpha and beta subunits was demonstrated, thereby confirming the assembly of both subunits into an active enzyme. Deficiency of either alpha PCC or beta PCC results in propionic acidemia, an autosomal recessive disorder. We used this expression system to characterize one missense mutation previously described in five Japanese alleles, namely C1283T (Thr428lle) in beta PCC. This mutation, when expressed in E.coli under the same conditions as that of wild-type PCC, had null activity, despite the presence of assembled alpha PCC and beta PCC subunits. This bacterial expression system can be useful for analysis of either alpha PCC or beta PCC mutations. Our findings indicated that the groES and groEL chaperonin proteins were essential for folding and assembly of the human PCC heteromeric subunits.
Hum Mol Genet 1996 Mar
PMID:Chaperonin-mediated assembly of wild-type and mutant subunits of human propionyl-CoA carboxylase expressed in Escherichia coli. 885 56

Propionic acidemia is an autosomal recessive disorder caused by a deficiency in the mitochondrial enzyme propionyl-CoA carboxylase (PCC). PCC is composed of two subunits, alpha and beta, encoded by the PCCA and PCCB genes, respectively. We analyzed mutations of the PCCA gene using patients' fibroblasts diagnosed with alpha subunit deficiency. By RT-PCR, four of 12 cell lines examined appeared to have a larger transcript present at a level comparable with that of the expected normal species. Sequencing of the larger transcriptrevealed an 84 bp insertion at nt 1209 of the codingsequence. Its incorporation in the transcript results in translation termination due to the presence of two in-frame stop codons. The 84 bp insertion was found to originate from the intron between nt 1209 and 1210. Consensus splice donor and acceptor sites were found at the 3'- and 5'-ends of the insertion, respectively. The insertion was also found in the remaining eight cell lines as well as in normal cells, but at a muchreduced level compared with the normal lengthsequence. Mutation analysis of the four cell lines showing seemingly elevated levels of the insertion sequence revealed one nonsense mutation (R288X), two frameshift deletions (700del5 and 1115del4) and one splice mutation (1671IVS+5G-->C) as expressed alleles. We conclude that the common characteristic of the four cell lines is that they contain mRNA destabilizing mutations that reduce the mRNA level of the normal length sequence. Consequently, the low levels of cryptic mRNAs become detectable at a level similar to that of the residual level of the normal length mRNA. We suggest that screening for an increased proportion of the 84 bp insertion by RT-PCR can be used as a rapid assay for RNA destabilizing mutations. Our results suggest caution in associating such mutations with aberrant mRNA species, such as cryptic splice products, which may instead be part of the 'background noise' of the splicing machinery.
Hum Mol Genet 1999 Jan
PMID:Detection of a normally rare transcript in propionic acidemia patients with mRNA destabilizing mutations in the PCCA gene. 988 38

Although the role of vitamins as prosthetic groups of enzymes is well known, their participation in the regulation of their genetic expression has been much less explored. We studied the effect of biotin on the genetic expression of rat liver mitochondrial carboxylases: pyruvate carboxylase (PC), propionyl-CoA carboxylase (PCC), and 3-methylcrotonyl-CoA carboxylase (MCC). Rats were made biotin-deficient and were sacrificed after 8 to 10 weeks, when deficiency manifestations began to appear. At this time, hepatic PCC activity was 20% of the control values or lower, and there was an abnormally high urinary excretion of 3-hydroxyisovaleric acid, a marker of biotin deficiency. Biotin was added to deficient primary cultured hepatocytes. It took at least 24 h after the addition of biotin for PCC to achieve control activity and biotinylation levels, whereas PC became active and fully biotinylated in the first hour. The enzyme's mass was assessed in liver homogenates from biotin-deficient rats and incubated with biotin to convert the apocarboxylases into holocarboylases, which were detected by streptavidin blots. The amount of PC was minimally affected by biotin deficiency, whereas that of the alpha subunits of PCC and of MCC decreased substantially in deficient livers, which likely explains the reactivation and rebiotinylation results. The expression of PC and alphaPCC was studied at the mRNA level by Northern blots and RT/PCR; no significant changes were observed in the deficient livers. These results suggest that biotin regulates the expression of the catabolic carboxylases (PCC and MCC), that this regulation occurs after the posttranscriptional level, and that pyruvate carboxylase, a key enzyme for gluconeogenesis, Krebs cycle anaplerosis, and fatty acid synthesis, is spared of this control.
Mol Genet Metab 1999 Jan
PMID:Differential effects of biotin deficiency and replenishment on rat liver pyruvate and propionyl-CoA carboxylases and on their mRNAs. 997 43

Propionic acidemia is a rare autosomal recessive disorder of intermediary metabolism. It is caused by a deficiency of the mitochondrial enzyme propionyl-CoA carboxylase (PCC, EC 6.4.1.3), a heteropolymeric protein composed of two subunits, alpha and beta. PCC requires ATP and biotin as cofactors for the reaction, the latter enzymatically added onto the alpha subunit. We investigated coding sequence mutations in the alpha subunit of PCC by analyzing fibroblast RNA from propionic acidemia patients deficient in alpha subunit function by single-strand conformation polymorphism and direct sequencing. Five missense mutations and one short in-frame deletion were found among different patients. Four mutations were located in the putative biotin carboxylase domain, whereas the two others were within the 67-amino-acid C-terminal domain previously shown to be required to obtain biotinylation of the alpha subunit. We analyzed fibroblast extracts for the presence of a biotinylated alpha subunit by Western blot analysis using streptavidin coupled to alkaline phosphatase. Four of five cell lines failed to show a biotinylated alpha subunit, regardless of the position of the mutations within the coding sequence. Two mutations located in the biotinylation domain were expressed in an Escherichia coli-based system and shown to abolish biotinylation of the domain. The results suggest that most mutations have a severe impact on the stability or the functionality of the alpha subunit.
Mol Genet Metab 1999 May
PMID:Coding sequence mutations in the alpha subunit of propionyl-CoA carboxylase in patients with propionic acidemia. 1032 19

Propionyl-CoA carboxylase (PCC) catalyzes the biotin-dependent carboxylation of propionyl-CoA to d-methylmalonyl-CoA in the mitochondrial matrix. Human PCC is a dodecamer composed of pairs of nonidentical alpha and beta subunits encoded by PCCA and PCCB genes, respectively. Deficiency of PCC results in propionic acidemia (PA), a metabolic disorder characterized by severe metabolic ketoacidosis, vomiting, lethargy, and hypotonia. To date, almost 60 mutations have been reported in both genes. Exon 15 of the beta subunit is one of the two sites where a number of mutations have been identified in PA patients. In the primary betaPCC sequence, these mutations lead to three substitutions (R512C, L519P, and N536D), three truncations (R499X, R514X, and W531X), and one insertion (A51_R514insP). We expressed these mutant proteins in Escherichia coli in which the GroESL complex was overexpressed. The only mutation that does not impact the stability of mutant betaPCC in bacteria is W531X. The remaining mutations lead to either complete (L519P, N536D) or partial (R499X, R512C, A513_R514insP, and R514X) degradation of the mutant subunits. Size-exclusion chromatography revealed that R512C and W531X do not affect the assembly of alphaPCC and betaPCC to active oligomers. Specific activities for these mutant proteins, however, were only 3.9 and 10% of the wild type, respectively. Taken together, the carboxyl-terminal portion of 40 amino acid residues of the beta subunit affects the stability and the assembly of the alpha and beta subunits as well as the carboxylation of propionyl-CoA.
Mol Genet Metab 2000 Dec
PMID:Changes in the carboxyl terminus of the beta subunit of human propionyl-CoA carboxylase affect the oligomer assembly and catalysis: expression and characterization of seven patient-derived mutant forms of PCC in Escherichia coli. 1113 55

Anaplerosis, or de novo formation of intermediates of the tricarboxylic acid (TCA) cycle, compensates for losses of TCA cycle intermediates, especially alpha-ketoglutarate, from brain cells. Loss of alpha-ketoglutarate occurs through release of glutamate and GABA from neurons and through export of glutamine from glia, because these amino acids are alpha-ketoglutarate derivatives. Anaplerosis in the brain may involve four different carboxylating enzymes: malic enzyme, phosphoenopyruvate carboxykinase (PEPCK), propionyl-CoA carboxylase, and pyruvate carboxylase. Anaplerotic carboxylation was for many years thought to occur only in glia through pyruvate carboxylase; therefore, loss of transmitter glutamate and GABA from neurons was thought to be compensated by uptake of glutamine from glia. Recently, however, anaplerotic pyruvate carboxylation was demonstrated in glutamatergic neurons, meaning that these neurons to some extent can maintain transmitter synthesis independently of glutamine. Malic enzyme, which may carboxylate pyruvate, was recently detected in neurons. The available data suggest that neuronal and glial pyruvate carboxylation could operate at as much as 30% and 40-60% of the TCA cycle rate, respectively. Cerebral carboxylation reactions are probably balanced by decarboxylation reactions,, because cerebral CO2 formation equals O2 consumption. The finding of pyruvate carboxylation in neurons entails a major revision of the concept of the glutamine cycle.
Mol Neurobiol
PMID:Carboxylation and anaplerosis in neurons and glia. 1141 79

Propionyl-CoA carboxylase (PCC, EC 6.4.1.3) is a mitochondrial, biotin-dependent enzyme that functions in the catabolism of branched-chain amino acids, fatty acids with odd-numbered chain lengths, and other metabolites. It catalyzes the ATP-dependent carboxylation of propionyl-CoA to d-methylmalonyl-CoA. PCC is composed of two types of subunits, likely as alpha4beta4 or alpha6beta6, with the alpha subunit containing the covalently bound biotin prosthetic group. A genetic deficiency of PCC activity causes propionic acidemia, a potentially fatal disease with onset in severe cases in the newborn period. Affected patients may have mutations of either the PCCA or PCCB gene. In this study, we have determined the structure of the human PCCA gene which, at the present time, is only partially represented in the databases. Based on reported ESTs and confirmed by RT-PCR, we also redefine the translation initiation codon to a position 75 nucleotides upstream of the currently accepted initiation codon. We show the distribution of mutations, including three identified in this study, and renumber all reported mutations to count from the new initiation codon. The gene spans more than 360 kb and consists of 24 exons ranging from 37 to 335 bp in length. The introns range in size from 104.bp to 66 kb. We have also determined the nucleotide sequence of approximately 1 kb of the 5'-flanking region upstream of the ATG translation initiation site. The proximal 400 bp of the 5'-flanking region shows a high G + C content (67%) and is part of a putative 1-kb CpG island that extends into exon 1 and part of intron 1. The putative promoter lacks a TATA box but contains two AP-1 sites and a conservatively defined consensus GC box, the latter characteristic of the core binding sequence of the Sp1 transcription factor.
Mol Genet Metab
PMID:Structure of the PCCA gene and distribution of mutations causing propionic acidemia. 1159 20


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