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* Bacterial regulatory proteins, lacI family signature *
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The many bacterial transcription regulation proteins which bind DNA  through a
'helix-turn-helix' motif can  be  classified into subfamilies  on the basis of
sequence similarities. One of these subfamilies groups together [1,2]:

 - ascG, the ascBF operon repressor.
 - ccpA, a transcriptional  regulator  involved  in  catabolic  repression  of
   alpha-amylase in Bacillus subtilis.
 - cytR, a repressor of genes  such  as  deoCABD,  udp,  and cdd  which encode
   catabolizing enzymes; and  nupC,  nupG,  and  tsx encoding transporting and
   pore-forming proteins.
 - ebgR, the repressor for  the  genes coding for beta galactosidase alpha and
   beta subunits.
 - fruR (or shl), the fructose repressor. FruR is implicated in the regulation
   of a large number  of  operons  encoding  enzymes  which  comprise  central
   pathways of carbon metabolism.
 - galR, the galactose operon repressor.
 - galS, the mgl operon repressor and galactose ultrainduction factor.
 - lacI, the lactose operon repressor.
 - malI, a maltose regulon protein that represses the malXY genes.
 - nfxB, which  may  repress  the expression of genes that are associated with
   cell permeability to drugs such as guinolones in Pseudomonas aeruginosa.
 - opnR, the opine utilization repressor in Agrobacterium rhizogenes.
 - purF, a repressor for genes encoding purine nucleotide synthesis enzymes.
 - rafR, the raffinose operon repressor.
 - rbsR, the ribose operon repressor.
 - rbtR, the ribitol operon repressor.
 - scrR, the repressor for the scr operon in enteric bacteria.

Most of the proteins in this family recognize sugar-inducers. The 'helix-turn-
helix'  DNA-binding  motif  of  these  proteins  is  located in the N-terminal
extremity of the sequences.  The pattern we use to detect these proteins spans
the complete motif except for the last residue.

-Consensus pattern: [LIVM]-x-[DE]-[LIVM]-A-x(2)-[STAG]-x-V-[SP]-x(2)-[STAG]-
                    [LIVMA]-x(2)-[FLIVMAN]-[LIVMC]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for rafR.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Expert(s) to contact by email: Reizer J.
                                jreizer@ucsd.edu

-Last update: June 1994 / Pattern and text revised.

[ 1] Vartak N.B., Reizer J., Reizer A., Gripp J.T., Groisman E.A., Wu L.-F.,
     Tomich J.M., Saier M.H. Jr.
     Res. Microbiol. 142:951-963(1991).
[ 2] Weickert M.J., Adhya S.
     J. Biol. Chem. 267:15869-15874(1992).