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citB

Gene
citB
Protein
Aconitate/2-methylaconitate hydratase
Organism
Bacillus subtilis (strain 168)
Length
909 amino acids
Function
Involved in both the tricarboxylic acid (TCA) and methylcitric acid cycles (PubMed:28956599). Catalyzes the reversible isomerization of citrate to isocitrate via cis-aconitate (PubMed:3110133, PubMed:23354745). Also catalyzes the rehydration of 2-methyl-cis-aconitate to produce 2-methylisocitrate (PubMed:28956599). The apo form of AcnA functions as a RNA-binding regulatory protein which plays a role in the regulation of citrate concentration and in the sporulation. To prevent the accumulation of excessive levels of citrate, it binds near the 5' end of the citZ mRNA, decreasing its stability and thereby limiting the concentration of citrate synthase in the cell. Aconitase also binds to the gerE transcript late in sporulation and stabilizes it for translation, thereby increasing the rate and level of GerE protein accumulation (PubMed:10468622, PubMed:16923907, PubMed:23354745, PubMed:9393699).
Similarity
Belongs to the aconitase/IPM isomerase family.
Mass
99.334 kDa
Sequence
MANEQKTAAKDVFQARKTFTTNGKTYHYYSLKALEDSGIGKVSKLPYSIKVLLESVLRQVDGFVIKKEHVENLAKWGTAELKDIDVPFKPSRVILQDFTGVPAVVDLASLRKAMAAVGGDPDKINPEIPVDLVIDHSVQVDKAGTEDALAVNMDLEFERNAERYKFLSWAKKAFNNYQAVPPATGIVHQVNLEFLASVVHAIEEDGELVTYPDTLVGTDSHTTMINGIGVLGWGVGGIEAEAGMLGQPSYFPVPEVIGAKLVGKLPNGTTATDLALKVTQVLREKGVVGKFVEFFGPGIAELPLADRATIANMAPEYGATCGFFPVDEEALNYLRLTGRDPEHIDVVEAYCRSNGLFYTPDAEDPQFTDVVEIDLSQIEANLSGPKRPQDLIPLSAMQETFKKQLVSPAGNQGFGLNAEEENKEIKFKLLNGEETVMKTGAIAIAAITSCTNTSNPYVLIGAGLVAKKAVELGLKVPNYVKTSLAPGSKVVTGYLVNSGLLPYMKELGFNLVGYGCTTCIGNSGPLSPEIEEAVAKNDLLITSVLSGNRNFEGRIHPLVKGNYLASPPLVVAYALAGTVNINLKTDPIGVGKDGQNVYFNDIWPSMDEINALVKQTVTPELFRKEYETVFDDNKRWNEIETTDEALYKWDNDSTYIQNPPFFEEMSVEPGKVEPLKGLRVVGKFGDSVTTDHISPAGAIGKDTPAGKYLQEKGVSPRDFNSYGSRRGNHEVMMRGTFANIRIKNQIAPGTEGGFTTYWPTGEVTSIYDACMKYKEDKTGLVVLAGKDYGMGSSRDWAAKGTNLLGIRTVIAESFERIHRSNLVFMGVLPLQFKQGENADTLGLTGKEVIEVDVDETVRPRDLVTVRAINEDGNVTTFEAVVRFDSEVEIDYYRHGGILQMVLREKMKQS

Gene
citB
Protein
Citrate utilization protein B
Organism
Escherichia coli
Length
379 amino acids
Mass
41.797 kDa
Sequence
MKQLEKLIIEAKILTEPEAEVERVMQVCNACRYCEGFCAVFPAMTQRLEFGKADINYLANLCHNCGACLHACQYAPPHEFAINVPKAMAEVRLETYQHYAQPAAFGALYRQAGVTVTLALVFSLILFLLLAMGLKGSLLHPPLAGDFYQIFPHNLLAWMFGSVFMLAIGLLMAGVIRFWREISPVGPRPAEIAEASHNALTLKYLDGGHGKGCNEADDAFTLMRRRFHHFTFYGFMLCFAATVVATGYHYFAGWEAPYPFFSVPVMLGTLGGIGLIVGPAGLLWLNLKRSSLHGDARQKPMDRGFILLLLLTSLTGIGLLAGRDTSWMGILLAIHLGVVMALFLTIPYGKFAHGFYRCASLLKWAIEKRRGKQAGVAGD

Gene
citB
Protein
Citrate utilization protein B
Organism
Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)
Length
379 amino acids
Mass
41.549 kDa
Sequence
MKQLEKLIIEATVLTEPEAEVERVMQVCNACRYCEGFCAVFPAMTQRLEFGKADIHYLANLCHNCGACLHACQYAPPHEFAINVPKAMAQARLETYQQYAQPAAFGALYRRAGITVALALIVGLTLFLLLAMALKGSLIHPPLAGDFYQIFPHSLLAWMFGSVFVLAIGLLMAGVIRFWREISPGVPRSAEIAEASHNALTLKYLDGGHGKGCNEADDAFTLLRRRFHHFTFYGFMLCFAATVVATGYHYVAGWEAPYPFFSLPVMLGTLGGIGLLIGPAGLLWLNLRRSPLHGDARQKPMDRGFILLLFLTSLTGLALLAGRDTSGMGILLALHLGVVMALFLTLPYGKFAHGFFRCAALLKWAVEKRRGKHAGDTGN

Gene
citB
Protein
2-oxoglutarate-dependent dioxygenase citB
Organism
Monascus ruber
Length
329 amino acids
Function
2-oxoglutarate-dependent dioxygenase; part of the gene cluster that mediates the biosynthesis of the mycotoxin citrinin, a hepato-nephrotoxic compound to humans due to inhibition of respiration complex III (Ref.1). The pathway begins with the synthesis of a keto-aldehyde intermediate by the citrinin PKS (pksCT also named citS) from successive condensations of 4 malonyl-CoA units, presumably with a simple acetyl-CoA starter unit (Ref.1). Release of the keto-aldehyde intermediate is consistent with the presence of the C-terminal reductive release domain (Ref.1). The exact catalytic role of the hydrolase citA remains mysterious, although it is clear that it increases the productivity of the PKS and performs the earliest non-PKS step during citrinin biosynthesis (Ref.1). CitB then catalyzes the oxidation of the C-12 methyl of the ketone intermediate to an alcohol intermediate which is further oxidized by the oxidoreductase citC to produce a bisaldehyde intermediate (Ref.1). The fourth catalytic step is catalyzed by the citD aldehyde dehydrogenase (Ref.1). The final transformation is the reduction of C-3 by citE to provide the chemically stable citrinin nucleus (Ref.1). CitE appears highly selective for its substrate as its presence in any context other than a full complement of citS and citA-D does not result in observable new compounds (Ref.1).
Similarity
Belongs to the iron/ascorbate-dependent oxidoreductase family.
Mass
36.894 kDa
Sequence
MPISTKSSFYLPAVDISPYLQDPNSDAARKVIDDVRAACTSTGFFQLLGHGISPALQQSVFAAAAKFFALPSDVKSRCRNVGFRGYDPMASQSYELGVLPDLKEGFIAGKDIPLDDPRVASQRFFMGQNAWPPSELLPEANFRRPIEEYYQAMLKLCWVVLDLVAATLPYGPHVFDEFKENDPACPLRLLHYPPAPAPDVAKGRQLGSSAHTDFGAITLLLQDDHSGLEVQDCETGEWIGVPPNKDAYVVNLGDMMSRITRGHYKSSIHRVINQNLTDRYSVVFFFDGNLDYRLRPLDRVGQNWDEEDTLTVEEHMLERTTTTYNLKVK

Gene
citB
Protein
Transcriptional regulatory protein CitB
Organism
Klebsiella pneumoniae
Length
234 amino acids
Function
Member of the two-component regulatory system CitA/CitB essential for expression of citrate-specific fermentation genes. Phosphorylated CitB binds to two sites in the citS-citC intergenic region where it probably activates transcription of both genes.
Mass
26.821 kDa
Sequence
MDSITTLIVEDEPMLAEILVDNIKQFPQFDVIGIADKLESARKQLRLYQPQLILLDNFLPDGKGIDLIRHAVSTHYKGRIIFITADNHMETISEALRLGVFDYLIKPVHYQRLQHTLERFARYRSSLRSSEQASQLHVDALFNIQAREQTEPASAPLRGIDESTFQRVLQLFADPTVVHTADSLARILGSSKTTARRYLEQGVKNDFLEAEISYGKVGRPERIYHGKQTYPEQR