{PDOC00331}
{PS00394; DNA_PHOTOLYASES_1_1}
{PS00691; DNA_PHOTOLYASES_1_2}
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* DNA photolyases class 1 signatures *
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Deoxyribodipyrimidine photolyase (EC 4.1.99.3) (DNA photolyase) [1,2] is a DNA
repair enzyme. It   binds to UV-damaged DNA containing  pyrimidine dimers and,
upon absorbing  a  near-UV photon (300 to 500 nm), breaks the cyclobutane ring
joining the  two  pyrimidines   of the dimer. DNA photolyase is an enzyme that
requires two  choromophore-cofactors  for  its  activity:  a reduced FADH2 and
either 5,10-methenyltetrahydrofolate  (5,10-MTFH)  or an oxidized 8-hydroxy-5-
deazaflavin (8-HDF)  derivative  (F420). The folate or deazaflavin chromophore
appears to  function  as an antenna, while the FADH2 chromophore is thought to
be responsible  for  electron  transfer. On the basis of sequence similarities
[3] DNA photolyases  can be grouped into two classes. The first class contains
enzymes from   Gram-negative   and   Gram-positive  bacteria,  the  halophilic
archaebacteria Halobacterium halobium,  fungi and plants. Class 1 enzymes bind
either 5,10-MTHF (E.coli, fungi, etc.) or 8-HDF (S.griseus, H.halobium).

This family  also  includes  Arabidopsis  cryptochromes 1 (CRY1) and 2 (CRY2),
which are  blue  light  photoreceptors that  mediate  blue  light-induced gene
expression.

There are  a  number  of  conserved  sequence regions in all known class 1 DNA
photolyases, especially in  the  C-terminal  part.  We  selected  two of these
regions as signature patterns.

-Consensus pattern: T-G-x-P-[LIVM](2)-D-A-x-M-[RA]-x-[LIVM]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Consensus pattern: [DN]-R-x-R-[LIVM]-[LIVMN]-x-[STA]-[STAQ]-F-[LIVMFA]-x-K-x-
                    L-x(2,3)-W-[KRQ]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Note: See also the entry for class 2 DNA photolyases (see <PDOC00832>).

-Last update: December 2004 / Pattern and text revised.

[ 1] Sancar G.B., Sancar A.
     Trends Biochem. Sci. 12:259-261(1987).
[ 2] Jorns M.S.
     "DNA photorepair: chromophore composition and function in two classes
     of DNA photolyases."
     Biofactors 2:207-211(1990).
     PubMed=2282137
[ 3] Yasui A., Eker A.P.M., Yasuhira S., Yajima H., Kobayashi T., Takao M.,
     Oikawa A.
     "A new class of DNA photolyases present in various organisms including
     aplacental mammals."
     EMBO J. 13:6143-6151(1994).
     PubMed=7813451
[ 4] Lin C., Ahmad M., Cashmore A.R.
     "Arabidopsis cryptochrome 1 is a soluble protein mediating blue
     light-dependent regulation of plant growth and development."
     Plant J. 10:893-902(1996).
     PubMed=8953250

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