Structural analysis of the human Golgi-associated plant pathogenesis related protein GAPR-1 implicates dimerization as a regulatory mechanism.
The plant pathogenesis related proteins group 1 (PR-1) and a variety of related mammalian proteins constitute a PR-1 protein family that share sequence and structural similarities. GAPR-1 is a unique family member as thus far it is the only PR-1 family member that is not co-translationally targeted to the lumen of the endoplasmic reticulum before trafficking to either vacuoles or secretion. Here we report that GAPR-1 may form dimers in vitro and in vivo, as determined by yeast two-hybrid screening, biochemical and biophysical assays. The 1.55A crystal structure demonstrates that GAPR-1 is structurally homologous to the other PR-1 family members previously solved (p14a and Ves V 5). Through an examination of inter-molecular interactions between GAPR-1 molecules in the crystal lattice, we propose a number of the highly conserved amino acid residues of the PR-1 family to be involved in the regulation of dimer formation of GAPR-1 with potential implications for other PR-1 family members. We show that mutagenesis of these conserved amino acid residues leads to a greatly increased dimer population. A recent report suggests that PR-1 family members may exhibit serine protease activity and further examination of the dimer interface of GAPR-1 indicates that a catalytic triad similar to that of serine proteases may be formed across the dimer interface by residues from both molecules within the dimer.
Serrano
Ramon L
RL
Biochemie-Zentrum Heidelberg, University of Heidelberg, Im Neuenheimerfeld 328, 69120 Heidelberg, Germany.
Kuhn
Audrey
A
Hendricks
Astrid
A
Helms
J Bernd
JB
Sinning
Irmgard
I
Groves
Matthew R
MR
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D006056:Golgi Apparatus / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
C458481:GLIPR2 protein, human; D008565:Membrane Proteins