Af. Neuwald et T. Hirano, HEAT repeats associated with condensins, cohesins, and other complexes involved in chromosome-related functions, GENOME RES, 10(10), 2000, pp. 1445-1452
HEAT repeats correspond to tandemly arranged curlicue-like structures that
appear to serve as flexible scaffolding on which other components can assem
ble. Using sensitive sequence analysis techniques we detected HEAT repeals
in various chromosome-associated proteins, including four Families of prote
ins associated with condensins and cohesins, which are nuclear complexes th
at contain structural maintenance of chromosome (SMC) proteins. Among the p
roteins detected were the XCAP-D2 and XCAP-G subunits of the Xenopus laevis
13S condensin complex, the Aspergillus BimD and Sordaria macrospora Spo76p
proteins, the budding yeast Scc2p protein, and the related Drosophila tran
scriptional activator Nipped-B. Clathrin adaptor and COP-I coatomer subunit
s, which Function in vesicle coat assembly and were previously noted to sha
re weak sequence similarity to condensin subunits, also contain HEAT repeat
s. HEAT repeats were also found in the TBP-associated TIP120 protein, a glo
bal enhancer of transcription, and in the budding yeast Motlp protein, whic
h is a member of the SWI2/SNF2 family. SWI2/SNF2 proteins, some of which ar
e helicases, perform diverse roles in transcription control, DNA repair, an
d chromosome segregation and form chromatin-remodeling complexes. HEAT repe
ats also were found in disl-TOG family and cofactor D family microtubule-as
sociated proteins, which, owing to their roles in microtubule dynamics, per
form functions related to mitotic progression and chromosome segregation. H
ence, our analysis predicts structural Features of these proteins and sugge
sts that HEAT repeats may play important roles in chromosome dynamics.