C. Stemmer et al., VARIABILITY IN ARABIDOPSIS-THALIANA CHROMOSOMAL HIGH-MOBILITY-GROUP-1-LIKE PROTEINS, European journal of biochemistry, 250(3), 1997, pp. 646-652
The vertebrate high-mobility-group (HMG) protein HMG1 is an abundant n
on-histone protein which is considered as an architectural element in
chromatin. In the monocotyledonous plant maize, four different HMG1-li
ke proteins (HMGa, HMGc1/2, HMGd) have been identified, whereas other
eukaryotes usually express only two different proteins of this type. W
e have examined here the HMG1-like proteins of the dicotyledonous plan
t Arabidopsis thaliana. The isolation and analysis of cDNAs encoding f
ive different so far uncharacterised HMG1-like proteins (now termed HM
G alpha, HMG beta 1/2, HMG gamma, HMG delta) from Arabidopsis indicate
s that the expression of multiple HMG1-like proteins is a general feat
ure of (higher) plants. The Arabidopsis HMG1-like proteins contain an
HMG domain as a common feature, but outside this conserved DNA-binding
motif the amino acid sequences are significantly different indicating
that this protein family displays a greater structural variability in
plants than in other eukaryotes. The five HMG1-like proteins were exp
ressed in Escherichia coli and purified. They bind with somewhat diffe
rent affinity to linear double-stranded DNA. The recognition of DNA st
ructure is evident from their preferential interaction with DNA minici
rcles relative to linear DNA. Reverse-transcribed PCR suggested that t
he five HMG1-like genes are simultaneously expressed in Arabidopsis le
aves and suspension culture cells.