ID   PRO_BPMU                Reviewed;         361 AA.
AC   Q01267; Q9T1W2; Q9T1W3;
DT   01-APR-1993, integrated into UniProtKB/Swiss-Prot.
DT   01-DEC-2000, sequence version 2.
DT   03-AUG-2022, entry version 84.
DE   RecName: Full=Protease I;
DE   AltName: Full=Gene product 32;
DE            Short=gp32;
DE   AltName: Full=Gene product I;
DE            Short=gpI;
GN   Name=I; Synonyms=Z; OrderedLocusNames=Mup32, Mup33;
OS   Escherichia phage Mu (Bacteriophage Mu).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Myoviridae; Muvirus.
OX   NCBI_TaxID=10677;
OH   NCBI_TaxID=543; Enterobacteriaceae.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA], PROTEIN SEQUENCE OF 242-249,
RP   IDENTIFICATION OF ISOFORM SCAFFOLD PROTEIN Z, AND FUNCTION.
RX   PubMed=11922669; DOI=10.1006/jmbi.2002.5437;
RA   Morgan G.J., Hatfull G.F., Casjens S., Hendrix R.W.;
RT   "Bacteriophage Mu genome sequence: analysis and comparison with Mu-like
RT   prophages in Haemophilus, Neisseria and Deinococcus.";
RL   J. Mol. Biol. 317:337-359(2002).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-58.
RX   PubMed=1385991; DOI=10.3109/10425179209030967;
RA   Baxa C.A., Chiang L., Howe M.M.;
RT   "DNA sequence characterization of the G gene region of bacteriophage Mu.";
RL   DNA Seq. 2:329-333(1992).
RN   [3]
RP   INDUCTION.
RX   PubMed=8293968; DOI=10.1093/genetics/135.3.619;
RA   Chiang L.W., Howe M.M.;
RT   "Mutational analysis of a C-dependent late promoter of bacteriophage Mu.";
RL   Genetics 135:619-629(1993).
RN   [4]
RP   FUNCTION, AND SUBUNIT.
RX   PubMed=8599204; DOI=10.1006/viro.1996.0107;
RA   Grimaud R.;
RT   "Bacteriophage Mu head assembly.";
RL   Virology 217:200-210(1996).
RN   [5]
RP   FUNCTION.
RX   PubMed=9495752; DOI=10.1128/jb.180.5.1148-1153.1998;
RA   Grimaud R., Toussaint A.;
RT   "Assembly of both the head and tail of bacteriophage Mu is blocked in
RT   Escherichia coli groEL and groES mutants.";
RL   J. Bacteriol. 180:1148-1153(1998).
CC   -!- FUNCTION: Protease I is involved in virion assembly and maturation.
CC       Protease I cleaves the portal protein to yield mature procapsids
CC       competent for DNA packaging (Probable). Isoform scaffold protein Z
CC       probably helps the capsid proteins to assemble into a functional capsid
CC       (Probable). {ECO:0000305|PubMed:11922669, ECO:0000305|PubMed:8599204,
CC       ECO:0000305|PubMed:9495752}.
CC   -!- SUBUNIT: [Protease I]: Might interact with viral portal protein; this
CC       interaction gives rise to an early 25S initiator complex (Probable).
CC       The scaffolding protein Z and the capsid protein T should then be added
CC       to the initiator complex to yield immature prohead (Probable). Host
CC       GroEL and GroES are also essential for the correct assembly of viral
CC       head. {ECO:0000269|PubMed:8599204, ECO:0000305}.
CC   -!- SUBCELLULAR LOCATION: Host cytoplasm {ECO:0000305}.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative initiation; Named isoforms=2;
CC       Name=Protease I;
CC         IsoId=Q01267-1; Sequence=Displayed;
CC       Name=Scaffold protein Z; Synonyms=Gene product Z, gpZ, gp33;
CC         IsoId=Q01267-2; Sequence=VSP_018866;
CC   -!- INDUCTION: Expressed in the late phase of the viral replicative cycle.
CC       Expression of late genes is activated by the viral late transcription
CC       activator C. {ECO:0000269|PubMed:8293968}.
CC   -!- PTM: The N-terminus is acetylated. {ECO:0000305}.
CC   -!- SIMILARITY: Belongs to the peptidase U35 family. {ECO:0000305}.
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DR   EMBL; AF083977; AAF01110.1; -; Genomic_DNA.
DR   EMBL; AF083977; AAF01111.1; -; Genomic_DNA.
DR   EMBL; M74911; AAA68902.1; -; Genomic_DNA.
DR   PIR; D56613; D56613.
DR   RefSeq; NP_050636.1; NC_000929.1.
DR   RefSeq; NP_050637.1; NC_000929.1.
DR   SMR; Q01267; -.
DR   GeneID; 2636253; -.
DR   GeneID; 2636276; -.
DR   KEGG; vg:2636253; -.
DR   KEGG; vg:2636276; -.
DR   Proteomes; UP000002611; Genome.
DR   GO; GO:0030430; C:host cell cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0008233; F:peptidase activity; IEA:UniProtKB-KW.
DR   GO; GO:0006508; P:proteolysis; IEA:UniProtKB-KW.
DR   GO; GO:0046797; P:viral procapsid maturation; IEA:UniProtKB-KW.
DR   InterPro; IPR012106; Phage_Mu_Gp1.
DR   Pfam; PF10123; Mu-like_Pro; 1.
DR   PIRSF; PIRSF016624; Mu_prophg_I; 1.
PE   1: Evidence at protein level;
KW   Acetylation; Alternative initiation; Direct protein sequencing;
KW   Host cytoplasm; Hydrolase; Late protein; Protease; Reference proteome;
KW   Viral capsid assembly; Viral capsid maturation;
KW   Viral release from host cell.
FT   CHAIN           1..361
FT                   /note="Protease I"
FT                   /id="PRO_0000028528"
FT   VAR_SEQ         1..178
FT                   /note="Missing (in isoform Scaffold protein Z)"
FT                   /evidence="ECO:0000305"
FT                   /id="VSP_018866"
SQ   SEQUENCE   361 AA;  38893 MW;  0DE858C2E48C7D46 CRC64;
     MKKHAIGIAA LNALSIDDDG WCQLLPAGHF SARDGRPFDV TGGQGWFIDG EIAGRLVEGV
     RALNQDVLID YEHNQLRKDK GLPPEQLVAA GWFNADEMQW REGEGLFIHP RWTAAAQQRI
     DDGEFGYLSA VFPYDTATGA VLQIRLAALT NDPGATGMKK LTALAADLPD ILQQENKPMN
     ETLRKLLARL GVTVPENADI TDEQATAALT ALDTLEINAG KVAALSAELE KAQKAAVDLT
     KYVPVESYNA LRDELAQATA QSATASLSAV LDKAEQEGRI FKSERTYLEQ LGGQIGVAAL
     SAQLEKKQPI AALSAMQTTT AKIPSQEKTA VAVLSADEQA AVKALGITEA EYLKMKQEQE
     K