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Cytochrome c biogenesis in Bacillus subtilis. Identification and analysis of ccdA

Schiött, Torbjörn LU (1999)
Abstract (Swedish)
Popular Abstract in Swedish

Cytokromer bär hem som prostetisk grupp och ingår i den energi givande andningskedjan. Cytokromer namnges beroende på strukturen av den hem-molekyl som respektive cytokrom bär. Cytokrom av a-typ innehåller hemA, cytokrom av b-typ innehåller hemB osv. Cytokrom av c-typ skiljer sig från övriga cytokrom genom att ha hemgruppen kovalent bunden till proteinet. Syntes av bakteriella c-typ cytokrom kräver en mängd olika faktorer. Det viktigaste steget i cytokrom c syntes, nämligen det kovalenta bindandet av hemgruppen till proteinet, sker på utsidan av det cytoplasmatiska membranet. Det betyder att både hemgruppen och proteinet måste transporteras separat över membranet innan sammankoppling kan ske.... (More)
Popular Abstract in Swedish

Cytokromer bär hem som prostetisk grupp och ingår i den energi givande andningskedjan. Cytokromer namnges beroende på strukturen av den hem-molekyl som respektive cytokrom bär. Cytokrom av a-typ innehåller hemA, cytokrom av b-typ innehåller hemB osv. Cytokrom av c-typ skiljer sig från övriga cytokrom genom att ha hemgruppen kovalent bunden till proteinet. Syntes av bakteriella c-typ cytokrom kräver en mängd olika faktorer. Det viktigaste steget i cytokrom c syntes, nämligen det kovalenta bindandet av hemgruppen till proteinet, sker på utsidan av det cytoplasmatiska membranet. Det betyder att både hemgruppen och proteinet måste transporteras separat över membranet innan sammankoppling kan ske. Bacillus subtilis är en Gram-positiv bakterie som kan bilda sporer under vissa tillväxtbetingelser. Bacillus subtilis innehåller fyra cytokrom av c-typ. De är alla bundna till membranet. Den hem-innehållande domänen exponeras däremot ut från membranet. En mutant som saknar alla c-typ cytokrom har isolerats och karakteriserats. Den muterade genen har klonats. Genen, som döpts till ccdA, kodar för ett integralt membranprotein som visar viss likhet med ett större protein, DsbD, från Escherichia coli. Mina studier har visat att CcdA proteinet krävs för syntes av både cytokrom av c-typ och syntes av sporer, vilket i sig är en indikation på att CcdA proteinet ej är direkt inblandat i varken cytokrom c eller spor syntes. Intill ccdA ligger två andra gener, vars funktion i bakterien är okänd. Dessa två gener kan inaktiveras utan någon uppenbar påverkan av cytokrom c innehållet eller förmågan att bilda sporer. DsbD tros spela en viktig roll vid bildandet av disulfidbryggor i periplasmatiska protein. Möjligen kan CcdA proteinet ha en liknande funktion. Skapande eller brytande av disulfidbryggor kan vara viktiga inslag i syntes av c-typ cytokrom. Spor syntes i sin tur kan kräva ett eller flera protein vars tre-dimensionella struktur, och därmed deras aktivitet, är beroende av disulfidbryggor. (Less)
Abstract
Cytochromes function in electron transfer reactions, e.g. in respiratory systems, and contain haem as a prosthetic group. Cytochromes of the c-type differ from other cytochromes in that haem is covalently attached, via thioether linkages, to two cysteine residues in a conserved sequence motif in the protein, Cys-Xaa-Yaa-Cys-His. The functional location of c-type cytochromes in bacteria is on the outer side of the cytoplasmic membrane. Haem and apocytochrome c polypeptide are synthesised in the cytoplasm but assembly of cytochrome c occurs on the outer side of the cytoplasmic membrane. Little is known about biogenesis of cytochromes c in Gram-positive bacteria. Bacillus subtilis is a Gram-positive, endospore forming, bacterium. It contains... (More)
Cytochromes function in electron transfer reactions, e.g. in respiratory systems, and contain haem as a prosthetic group. Cytochromes of the c-type differ from other cytochromes in that haem is covalently attached, via thioether linkages, to two cysteine residues in a conserved sequence motif in the protein, Cys-Xaa-Yaa-Cys-His. The functional location of c-type cytochromes in bacteria is on the outer side of the cytoplasmic membrane. Haem and apocytochrome c polypeptide are synthesised in the cytoplasm but assembly of cytochrome c occurs on the outer side of the cytoplasmic membrane. Little is known about biogenesis of cytochromes c in Gram-positive bacteria. Bacillus subtilis is a Gram-positive, endospore forming, bacterium. It contains four membrane-bound c-type cytochromes. A mutant with a pleiotropic cytochrome c deficiency has been isolated and characterised, leading to the identification of the ccdA gene. The CcdA protein is required for a late step of both cytochrome c and spore synthesis. The ccdA gene is co-transcribed with two downstream genes, yneI and yneJ. These genes, which are also transcribed from their own promoters, are not required for cytochrome c or spore synthesis. The ccdA promoter is weak and increases in activity at the end of the exponential growth phase. CcdA is a 26 kDa polytopic integral membrane protein with sequence similarity to the central, hydrophobic, domain of the larger E. coli DsbD protein. DsbD functions to reduce a disulphide isomerase(s) in the periplasm. CcdA homologues are found in Bacteria, Archae and plants. Conserved cysteine residues in these proteins (and also in DsbD-like proteins) may be involved in transfer of reducing equivalents across membranes. Redox chemistry on the outer side of the B. subtilis cytoplasmic membrane might be important for both cytochrome c and spore-synthesis, and affected in a ccdA null mutant. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Thöny-Meyer, Linda, Mikrobiologisches Institute, ETH, Zürich, Schweiz
organization
publishing date
type
Thesis
publication status
published
subject
keywords
spore synthesis, haem C, cytochrome c synthesis, Bacillus subtilis, ccdA, Microbiology, bacteriology, virology, mycology, Mikrobiologi, bakteriologi, virologi, mykologi
pages
142 pages
publisher
Department of Microbiology, Lund University
defense location
Blue lecture hall, Ecology Building, Sölvegatan 37, Lund
defense date
1999-03-05 10:15
external identifiers
  • Other:ISRN: LUNBDS/NBNB-1034/1-66
ISBN
91-628-3400-2
language
English
LU publication?
yes
id
418db615-4bd2-4dee-9b4c-61a243a25d5f (old id 39344)
date added to LUP
2007-07-31 16:51:23
date last changed
2016-09-19 08:45:03
@misc{418db615-4bd2-4dee-9b4c-61a243a25d5f,
  abstract     = {Cytochromes function in electron transfer reactions, e.g. in respiratory systems, and contain haem as a prosthetic group. Cytochromes of the c-type differ from other cytochromes in that haem is covalently attached, via thioether linkages, to two cysteine residues in a conserved sequence motif in the protein, Cys-Xaa-Yaa-Cys-His. The functional location of c-type cytochromes in bacteria is on the outer side of the cytoplasmic membrane. Haem and apocytochrome c polypeptide are synthesised in the cytoplasm but assembly of cytochrome c occurs on the outer side of the cytoplasmic membrane. Little is known about biogenesis of cytochromes c in Gram-positive bacteria. Bacillus subtilis is a Gram-positive, endospore forming, bacterium. It contains four membrane-bound c-type cytochromes. A mutant with a pleiotropic cytochrome c deficiency has been isolated and characterised, leading to the identification of the ccdA gene. The CcdA protein is required for a late step of both cytochrome c and spore synthesis. The ccdA gene is co-transcribed with two downstream genes, yneI and yneJ. These genes, which are also transcribed from their own promoters, are not required for cytochrome c or spore synthesis. The ccdA promoter is weak and increases in activity at the end of the exponential growth phase. CcdA is a 26 kDa polytopic integral membrane protein with sequence similarity to the central, hydrophobic, domain of the larger E. coli DsbD protein. DsbD functions to reduce a disulphide isomerase(s) in the periplasm. CcdA homologues are found in Bacteria, Archae and plants. Conserved cysteine residues in these proteins (and also in DsbD-like proteins) may be involved in transfer of reducing equivalents across membranes. Redox chemistry on the outer side of the B. subtilis cytoplasmic membrane might be important for both cytochrome c and spore-synthesis, and affected in a ccdA null mutant.},
  author       = {Schiött, Torbjörn},
  isbn         = {91-628-3400-2},
  keyword      = {spore synthesis,haem C,cytochrome c synthesis,Bacillus subtilis,ccdA,Microbiology,bacteriology,virology,mycology,Mikrobiologi,bakteriologi,virologi,mykologi},
  language     = {eng},
  pages        = {142},
  publisher    = {ARRAY(0xa37b378)},
  title        = {Cytochrome c biogenesis in Bacillus subtilis. Identification and analysis of ccdA},
  year         = {1999},
}