ID   GRDI_PEPAC              Reviewed;         442 AA.
AC   O69406;
DT   16-JAN-2004, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1998, sequence version 1.
DT   25-MAY-2022, entry version 51.
DE   RecName: Full=Betaine reductase complex component B subunit alpha;
DE            EC=1.21.4.4;
DE   AltName: Full=Selenoprotein PB alpha;
GN   Name=grdI;
OS   Peptoclostridium acidaminophilum (Eubacterium acidaminophilum).
OC   Bacteria; Firmicutes; Clostridia; Eubacteriales; Peptostreptococcaceae;
OC   Peptoclostridium.
OX   NCBI_TaxID=1731;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ATCC 49065 / DSM 3953 / al-2;
RA   Sonntag D., Soehling B., Andreesen J.R.;
RL   Submitted (APR-1998) to the EMBL/GenBank/DDBJ databases.
RN   [2]
RP   PROTEIN SEQUENCE OF 1-38, AND CHARACTERIZATION.
RC   STRAIN=ATCC 49065 / DSM 3953 / al-2;
RX   PubMed=8529639; DOI=10.1111/j.1432-1033.1995.184_c.x;
RA   Meyer M., Granderath K., Andreesen J.R.;
RT   "Purification and characterization of protein PB of betaine reductase and
RT   its relationship to the corresponding proteins glycine reductase and
RT   sarcosine reductase from Eubacterium acidaminophilum.";
RL   Eur. J. Biochem. 234:184-191(1995).
CC   -!- FUNCTION: In the first step of betaine reductase, the substrate is
CC       bound to component PB via a Schiff base intermediate. Then the PB-
CC       activated substrate is nucleophilically attacked by the selenol anion
CC       of component PA to transform it to a carboxymethylated selenoether and
CC       the respective amine. By action of component PC, acetyl phosphate is
CC       formed, leaving component PA in its oxidized state. Finally component
CC       PA becomes reduced by the thioredoxin system to start a new catalytic
CC       cycle of reductive deamination.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=[thioredoxin]-disulfide + acetyl phosphate + H2O +
CC         trimethylamine = [thioredoxin]-dithiol + glycine betaine + H(+) +
CC         phosphate; Xref=Rhea:RHEA:11848, Rhea:RHEA-COMP:10698, Rhea:RHEA-
CC         COMP:10700, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:17750,
CC         ChEBI:CHEBI:22191, ChEBI:CHEBI:29950, ChEBI:CHEBI:43474,
CC         ChEBI:CHEBI:50058, ChEBI:CHEBI:58389; EC=1.21.4.4;
CC   -!- SUBUNIT: Heterotetramer of two alpha and two beta subunits. Component
CC       of the betaine reductase complex, together with components A and C. PB
CC       is substrate specific.
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DR   EMBL; Y17145; CAA76650.1; -; Genomic_DNA.
DR   PIR; S63508; S63508.
DR   AlphaFoldDB; O69406; -.
DR   GO; GO:0033795; F:betaine reductase activity; IEA:UniProtKB-EC.
DR   InterPro; IPR016585; Gly/sarc/bet_Rdtase_B_asu/bsu.
DR   InterPro; IPR015417; Gly_reductase_pB_sua/b.
DR   Pfam; PF09338; Gly_reductase; 1.
DR   PIRSF; PIRSF011588; Gly_sarc_betain_red_a/b; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Oxidoreductase.
FT   CHAIN           1..442
FT                   /note="Betaine reductase complex component B subunit alpha"
FT                   /id="PRO_0000083845"
SQ   SEQUENCE   442 AA;  48765 MW;  29EFFBD5112C7009 CRC64;
     MKLELGNFYV EEIVFGEKTS FKDGVLTINK QEALDYVMED ENITHAELHI VKPGDMVRLC
     PVKEAIEPRI KLDGRTYFPG VTDEELTRCG EGRTHALKGC SVLVVGKHWG GFQDGLIDMG
     GEGAKYTYYS TLKNIVLVGD TNEDFEKNEQ QKKNKALRWA GHKLAEYIGK TVKDMEPQEV
     ETYELEPVTQ RSEEVTKLPG VVFVMQPQSQ MEELGYNDMV YGWDMNRMVP TYMHPNEVLD
     GAIISGSFMP CSSKWSTYDF QNFPALKRLY AEHGKTVNFL GVIMSNLNVA LQQKQRSALF
     VAQMAKSLGA QGAIVAEEGY GNPDADFIAC IVALENEGIK TVGLTNECTG RDGFSQPLVT
     LDEKANAIVS CGNVSELVEL PPMPVVLGEL EALARDGLSG GWAGDEILGS SVKADGSVIM
     ENNAMFCGDQ VVGWSTKTMK EF