{PDOC00283}
{PS00314; ICE_NUCLEATION}
{BEGIN}
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* Bacterial ice-nucleation proteins octamer repeat *
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Some Gram-negative bacteria  express proteins that  enable them to promote the
nucleation of ice at relatively high temperature (above -5 degree Celsius) [1,
2,3]. These proteins are localized at the surface of the outer membrane of the
bacteria and  can  cause  frost  injury  to  many  plant  species. The primary
structure of  these   ice-nucleation proteins is highly repetitive.  A central
repetitive domain  represents about 80% of the total sequence.  This domain is
mainly formed  by the repetition of a conserved region of forty eight residues
(48-mer).  The 48-mers are themselves composed of three blocks  of 16 residues
(16-mer). The  first eight residues of each of these 16-mers are identical. It
has been proposed that the repetitive domain  may be  directly responsible for
aligning water molecules in the seed crystal.

Schematic structure of a 48-mer region:

              [.........48.residues.repeated.domain..........]
             /              / |              | \              \
            AGYGSTxTagxxssli  AGYGSTxTagxxsxlt  AGYGSTxTaqxxsxlt
            [16.residues...]  [16.residues...]  [16.residues...]

-Consensus pattern: A-G-Y-G-S-T-x-T
-Sequences known to belong to this class detected by the pattern: ALL.    This
 octamer sequence  is found more  than forty  times  in each of the known ice-
 nucleation proteins.
-Other sequence(s) detected in Swiss-Prot: Paramecium primaurelia 168G surface
 protein (contains only one copy of the repeat).
-Last update: June 1994 / Text revised.

[ 1] Wolber P., Warren G.
     "Bacterial ice-nucleation proteins."
     Trends Biochem. Sci. 14:179-182(1989).
     PubMed=2672438
[ 2] Wolber P.K.
     Adv. Microb. Physiol. 34:205-237(1992).
[ 3] Gurian-Sherman D., Lindow S.E.
     FASEB J. 7:1338-1343(1993).

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