TABLE 2.
Summary of unique substitutions in alleles that were A− in the transient expression assay
| Allele | Individual | No. and type of unique substitutions | Position of nonconservative substitutions | Putative function of subdomain in which nonconservative substitution was found |
|---|---|---|---|---|
| chi558 | LA2750 (1) | 2 C,a 1 Nb | S135F: junction of domains V and VIa | Region forms an extended chain between two α-helices, important for anchoring the ATP molecule |
| chi487 | LA2884 (7177) | 1 N | A313Ec: outside domain XI, close to C terminus | The structure and function of this region is undefinede |
| peru592 | LA3636 (7252) | 1 C, 2 N | R217G: domain IX S135Fd | Exposed part of the activation domain |
| peru570 | LA3636 (7258) | 2 N | I168T: catalytic loop region P178T: domain VII in the β-sheet, upstream of activation domain | Phosphoryl-catalysis and transfer |
| hir46f | LA1775 (7219) | 2 C, 1 N | C104F: domain IV | Forms a large hydrophobic β-strand in the small lobe of the protein |
a
Conservative amino acid substitution.
b
Nonconservative amino acid substitution.
c
The introduction of aspartic acid at this position in the functional Pto allele from L. pimpinellifolium results in the loss of HR in the transient assay. Also the gain-of-function phenotype is lost when this substitution is made in the constitutively active form of Pto (L205D).
d
See chi558 allele.
f
Yeast-two-hybrid analysis demonstrated that this allele failed to bind the AvrPto ligand in yeast.