>TIGR00212 hemC porphobilinogen deaminase; InterPro: IPR000860 Tetrapyrroles are large macrocyclic compounds derived from a common biosynthetic pathway . The end-product, uroporphyrinogen III, is used to synthesise a number of important molecules, including vitamin B12, haem, sirohaem, chlorophyll, coenzyme F430 and phytochromobilin . The first stage in tetrapyrrole synthesis is the synthesis of 5-aminoaevulinic acid ALA via two possible routes: (1) condensation of succinyl CoA and glycine (C4 pathway) using ALA synthase (2.3.1.37 from EC), or (2) decarboxylation of glutamate (C5 pathway) via three different enzymes, glutamyl-tRNA synthetase (6.1.1.17 from EC) to charge a tRNA with glutamate, glutamyl-tRNA reductase (1.2.1.70 from EC) to reduce glutamyl-tRNA to glutamate-1-semialdehyde (GSA), and GSA aminotransferase (5.4.3.8 from EC) to catalyse a transamination reaction to produce ALA. The second stage is to convert ALA to uroporphyrinogen III, the first macrocyclic tetrapyrrolic structure in the pathway. This is achieved by the action of three enzymes in one common pathway: porphobilinogen (PBG) synthase (or ALA dehydratase, 4.2.1.24 from EC) to condense two ALA molecules to generate porphobilinogen; hydroxymethylbilane synthase (or PBG deaminase, 2.5.1.61 from EC) to polymerise four PBG molecules into preuroporphyrinogen (tetrapyrrole structure); and uroporphyrinogen III synthase (4.2.1.75 from EC) to link two pyrrole units together (rings A and D) to yield uroporphyrinogen III. Uroporphyrinogen III is the first branch point of the pathway. To synthesise cobalamin (vitamin B12), sirohaem, and coenzyme F430, uroporphyrinogen III needs to be converted into precorrin-2 by the action of uroporphyrinogen III methyltransferase (2.1.1.107 from EC). To synthesise haem and chlorophyll, uroporphyrinogen III needs to be decarboxylated into coproporphyrinogen III by the action of uroporphyrinogen III decarboxylase (4.1.1.37 from EC) . This entry represents hydroxymethylbilane synthase (or porphobilinogen deaminase, 2.5.1.61 from EC), which functions during the second stage of tetrapyrrole biosynthesis. This enzyme catalyses the polymerisation of four PBG molecules into the tetrapyrrole structure, preuroporphyrinogen, with the concomitant release of four molecules of ammonia. This enzyme uses a unique dipyrro-methane cofactor made from two molecules of PBG, which is covalently attached to a cysteine side chain. The tetrapyrrole product is synthesized in an ordered, sequential fashion, by initial attachment of the first pyrrole unit (ring A) to the cofactor, followed by subsequent additions of the remaining pyrrole units (rings B, C, D) to the growing pyrrole chain . The link between the pyrrole ring and the cofactor is broken once all the pyrroles have been added. This enzyme is folded into three distinct domains that enclose a single, large active site that makes use of an aspartic acid as its one essential catalytic residue, acting as a general acid/base during catalysis , . A deficiency of hydroxymethylbilane synthase is implicated in the neuropathic disease, Acute Intermittent Porphyria (AIP) . ; GO: 0004418 hydroxymethylbilane synthase activity, 0033014 tetrapyrrole biosynthetic process.

Probab=100.00 E-value=0 Score=814.43 Aligned_cols=294 Identities=46% Similarity=0.673 Sum_probs=286.2 Q ss_pred EEEEECCCHHHHHHHHHHHHHHHHHCCCCCCEEEEEEEEEECCCCCCCC-HHHCCCHHHHHHHHHHHHHCCCCEEEEECC Q ss_conf 8997079888899999999999974089983389999973274115875-567486226999999998709836997403 Q gi|254781037|r 6 FRIGTRCSPLALAHAFETRSSLMDVHKIPPHNIVIIPLSTKGDRITNRT-LTEIGGKGLFTEEIEKKLISGEIDCAVHSA 84 (307) Q Consensus 6 i~IgtR~S~LAl~Qa~~v~~~L~~~~~~p~~~~ei~~i~T~GD~~~~~~-l~~~g~kg~Ftkele~aLl~g~iDiAVHSl 84 (307) T Consensus 1 l~IGTRgS~LAl~Qa~~V~~~l~~~~~-p~~~~ei~~~kT~GD~~~~~~~L~~~GgKGlFtKEle~aLL~geiD~AVHSl 79 (312) T TIGR00212 1 LRIGTRGSKLALAQANLVKEQLKEVYP-PELDTEIVIIKTTGDKIQDKPLLSDIGGKGLFTKELEQALLDGEIDLAVHSL 79 (312) T ss_pred CEEECCCCHHHHHHHHHHHHHHHHHCC-CCCCEEEEEEEECCCCCCCCCCEEECCCHHHHHHHHHHHHHCCCCCEEEECC T ss_conf 978404868999999999999997369-7402179999804861116100021375036688999996259844888430 Q ss_pred CCCCCCC-CCCCEEEEECCCCCCCEEEEECCCCCCCCCCCCCEEECCCCCHHHHHHHHHCCCCCHHHCCCHHHHHHHHHC Q ss_conf 4321110-122101222365683105665243243324567322047530288899842377310330767999998637 Q gi|254781037|r 85 KDMPTKL-LKGLQISAYLPREDIRDVFISHTAQSLKDLALHSVIGTSSLRRKALLLRWRSDISVIDFRGKIETRLNKLNN 163 (307) Q Consensus 85 KDlP~~~-~~~l~i~a~~~R~d~rD~lv~~~~~~l~~lp~~a~IGTsS~RR~aql~~~~p~l~~~~iRGNv~TRl~Kl~~ 163 (307) T Consensus 80 KD~P~~~~~~gL~~~a~~~RedP~D~l~s~~~~~l~~LP~GA~vGTSS~RR~aql~~~RPDl~~~~lRGNi~TRl~Kl~~ 159 (312) T TIGR00212 80 KDVPTVLSPEGLEIAAVLKREDPRDVLVSRKYLSLEELPQGAKVGTSSLRRKAQLKALRPDLEIEPLRGNIDTRLRKLDE 159 (312) T ss_pred CCCCCCCCCCCCEEEEECCCCCCCCEEEECCCCCHHHCCCCCEEECCHHHHHHHHHHCCCCCEEEECCCCHHHHHHHHCC T ss_conf 23576559888278635587886426886278885127798889745799999998308994499746987999998518 Q ss_pred -CCCCEEEEEHHHHHHCCCC-CCCCCCCCHHHCCCCCCCCEEEEEEECCCCHHHHHHHHHCCHHHHHHHHHHHHHHHHHC Q ss_conf -8765563014545421621-12223368667358543207899985276124556776239788888788999998717 Q gi|254781037|r 164 -NKAHAILLAYAGIKRLKKE-KVIKEILNIEDFPPSPGQGAICIETHVNNPKAQELVKVINHEDTWDSVNCERAFLAELD 241 (307) Q Consensus 164 -g~~DaiilA~Agl~RL~l~-~~i~~~l~~~~~~PA~gQGaIaIe~r~~d~~i~~il~~Ind~~T~~~v~aER~fL~~L~ 241 (307) T Consensus 160 Gg~~DAiiLA~AGL~RLg~~~~~i~~~~~~~~~~PA~GQG~i~ve~R~dD~~~~~il~~i~h~~t~~~~~aER~fL~~L~ 239 (312) T TIGR00212 160 GGEYDAIILAAAGLKRLGLENDVITEVLDPEVMLPAVGQGAIAVECRKDDTEIKEILKEINHEETAVEVTAERAFLKELD 239 (312) T ss_pred CCCCHHHHHHHHHHHCCCCCCHHHHHCCCHHHCCCCCCCCEEEEEEECCCHHHHHHHHHCCCHHHHHHHHHHHHHHHHHC T ss_conf 88204899988875302541013431478114178866757999984587799998620288889999999999998728 Q ss_pred CCCCCCEEEEEEEECC-----EEEEEEEEECCCCC---EEEEEEEECCHH----HHHHHH--HHHHHHHHHHC Q ss_conf 7648852899999999-----89999999869987---899999843988----899999--99999999706 Q gi|254781037|r 242 GSCKSAIAGFAYCKGS-----TLYFYGIVLASDGK---IFHEVSRNGNRC----DAINIG--RDAAQYIRFIS 300 (307) Q Consensus 242 GgC~~PIGa~A~i~~~-----~l~l~a~v~s~DG~---~~i~~~~~g~~~----~a~~LG--~~la~~Ll~~g 300 (307) T Consensus 240 GgC~~Pig~~a~~~~~~~~t~~l~l~a~~~~~~G~~~~~~~~~~~~~~~~~~~~~~~~~G~~~~~A~~~~~~~ 312 (312) T TIGR00212 240 GGCQTPIGAYAEYEGDDNDTDKLKLKAVVLSLDGKIVREVIRAEKEGNIENKKEDAEELGNPLEVAEELLKRG 312 (312) T ss_pred CCCCCCEEEEEEEECCCCCCCEEEEEEEEECCCCCEEEEEHHHHHCCCHHHHHCCHHHCCCHHHHHHHHHHHC T ss_conf 8964331468898337788427999999971787164001001320313444105765067889999999719

HHsearch alignment for GI: 254781037 and conserved domain: TIGR00212