DOMAIN EXCHANGES BETWEEN KNAT3 AND KNAT1 SUGGEST SPECIFICITY OF THE KN1-LIKE HOMEODOMAINS REQUIRES SEQUENCES OUTSIDE OF THE 3RD HELIX AND N-TERMINAL ARM OF THE HOMEODOMAIN
Ka. Serikawa et Pc. Zambryski, DOMAIN EXCHANGES BETWEEN KNAT3 AND KNAT1 SUGGEST SPECIFICITY OF THE KN1-LIKE HOMEODOMAINS REQUIRES SEQUENCES OUTSIDE OF THE 3RD HELIX AND N-TERMINAL ARM OF THE HOMEODOMAIN, Plant journal, 11(4), 1997, pp. 863-869
Domain exchange constructs that traded regions surrounding the homeodo
main were constructed for two kn1-like genes, KNAT1 and KNAT3, and int
roduced into Arabidopsis thaliana under the control of the 35S CaMV pr
omoter. The kn1-like homeodomain proteins all have the homeodomain loc
ated near the C-terminus of the protein, and also share a second conse
rved domain (the ELK domain) immediately N-terminal to the homeodomain
. Progeny were scored for the appearance of the KNAT1 overexpression p
henotype. A construct containing the KNAT3 N-terminus and the KNAT1 EL
K- and homeodomain resulted in a KNAT1 overexpression phenotype, indic
ating that specificity mainly resides within the ELK- and homeodomain
region. Further exchanges demonstrated that specificity probably does
not arise from a single region within the ELK and/or homeodomain but r
ather requires sequences both N-terminal and C-terminal to residue 23
of the homeodomain. Further, in contrast to some animal homeodomains,
KNAT1 does not utilize the residues of the N-terminal arm of the homeo
domain far specificity.