{PDOC52028}
{PS52028; SMCR}
{PS52030; SMDRR}
{BEGIN}
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* Streptococcal M proteins C repeat and D repeats region profiles *
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M proteins  belong to a family of fibrous streptococcal surface proteins that
interact with  the  immune  system  of  the host and represent major virulence
factors due   to   their   antiphagocytic   activities.  These  antiphagocytic
properties are  explained  by binding to a variety of different host proteins,
with the most prominent one being fibrinogen. Another hypothesis relies on the
M-protein-mediated formation of large bacterial aggregates, thereby inhibiting
phagocytic engulfment. All M proteins share a common framework that includes a
conserved signal  peptide,  a  hypervariable  amino  terminus, a less variable
central domain,  and  a  highly  conserved  C-terminus.  A  number  of  repeat
sequences (A,  B,  C  and D repeats) follow the hypervariable region. Sequence
conservation increases from the A repeats to D repeats. The size and number of
the A  and  B  repeats varies between different M proteins. Most M proteins do
not possess  any  A  repeats.  The  C  repeats  are present in all M proteins,
although the  number  of  repeat sequences varies from two (M6) to four (M12).
The amino  acid  identity  in the C repeat region increases from C1 to C3. The
conserved repetitive C units are responsible for several biological activities
of M  and  M-like  proteins.  The C units are involved in the binding of human
serum albumin  (HSA)  to the M protein. Furthermore, the binding of complement
factor H  and  streptococcal  adherence  to  keratinocytes  in  human skin are
mediated by   the  C  units.  Region  D  is  composed  of  four  seven-residue
"quasirepeats" [1,2,3,4,5,6,7].

The M molecules exist as stable dimers the molecules are almost totally alpha-
helical. A  common  periodicity  in  the  placement of nonpolar or hydrophobic
residues is  responsible  for  maintaining  the alpha-helical character of the
proteins [1,2,3,4,5,6,7].  The  streptococcal M proteins C repeat can adopt an
alpha-helical structure (see <PDB:2KK9>) [8].

The profiles  we  developed  cover  respectively  the  entire  streptococcal M
proteins C repeat and D repeats region.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: July 2023 / First entry.

[ 1] Hollingshead S.K., Fischetti V.A., Scott J.R.
     "Complete nucleotide sequence of type 6 M protein of the group A
     Streptococcus.  Repetitive structure and membrane anchor."
     J. Biol. Chem. 261:1677-1686(1986).
     PubMed=3511046
[ 2] Mouw A.R., Beachey E.H., Burdett V.
     "Molecular evolution of streptococcal M protein: cloning and
     nucleotide sequence  of the type 24 M protein gene and relation to
     other genes of Streptococcus  pyogenes."
     J. Bacteriol. 170:676-684(1988).
     PubMed=3276665; DOI=10.1128/jb.170.2.676-684.1988
[ 3] Fischetti V.A.
     "Streptococcal M protein: molecular design and biological behavior."
     Clin. Microbiol. Rev. 2:285-314(1989).
     PubMed=2670192; DOI=10.1128/CMR.2.3.285
[ 4] O'Toole P.W., Stenberg L., Rissler M., Lindahl G.
     "Two major classes in the M protein family in group A streptococci."
     Proc. Natl. Acad. Sci. U. S. A. 89:8661-8665(1992).
     PubMed=1528877; DOI=10.1073/pnas.89.18.8661
[ 5] Gubbe K., Misselwitz R., Welfle K., Reichardt W., Schmidt K.H.,
     Welfle H.
     "C repeats of the streptococcal M1 protein achieve the human serum
     albumin binding  ability by flanking regions which stabilize the
     coiled-coil conformation."
     Biochemistry 36:8107-8113(1997).
     PubMed=9201959; DOI=10.1021/bi962991s
[ 6] Smeesters P.R., McMillan D.J., Sriprakash K.S.
     "The streptococcal M protein: a highly versatile molecule."
     Trends. Microbiol. 18:275-282(2010).
     PubMed=20347595; DOI=10.1016/j.tim.2010.02.007
[ 7] Fulde M., Rohde M., Polok A., Preissner K.T., Chhatwal G.S.,
     Bergmann S.
     "Cooperative plasminogen recruitment to the surface of Streptococcus
     canis via M  protein and enolase enhances bacterial survival."
     mBio 4:E00629-E00612(2013).
     PubMed=23481605; DOI=10.1128/mBio.00629-12
[ 8] Guilherme L., Alba M.P., Ferreira F.M., Oshiro S.E., Higa F.,
     Patarroyo M.E., Kalil J.
     "Anti-group A streptococcal vaccine epitope: structure, stability, and
     its ability  to interact with HLA class II molecules."
     J. Biol. Chem. 286:6989-6998(2011).
     PubMed=21169359; DOI=10.1074/jbc.M110.132118

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