Calculated flexibility of histone proteins correlate with mammalian histone H1 subtype.
We have calculated the polypeptide flexibility index for mammalian histone H1 sequences obtained from the National Center for Biotechnology Information Histone Sequence Database. This database contains over 1000 histone protein entries, from various species, compiled from SWISS_PROT, PIR, the Protein Data Bank (PDB), and CDS translations from GenBank. Histone H1 proteins were analyzed because of their critical role in chromatin structure and gene expression. Flexibility calculations revealed that histone subtype H1.0, which accumulates during terminal differentiation, has the highest flexibility index of all mammalian H1 subtypes. Other mammalian H1 subtypes had lower flexibility indices, including the human H1.2 subtype whose mRNA contains both a hairpin loop sequence and a poly(A) addition sequence. Histone mRNAs containing both of these structures have been shown to be expressed prior to and after terminal differentiation, yet these proteins do not necessarily accumulate in the chromatin of terminally differentiated cells. H1.2 and the H1.t have the lowest flexibility index (most ridged) of all human H1 subtypes. All human H1 proteins of the replication dependent subtypes have intermediate values for their flexibility indices.
Collart
D
D
Department of Biological Sciences, Clark Atlanta University, GA 30314, USA. dcollart@cau.edu
Seffens
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W
D016208:Databases, Factual; D006657:Histones / Q000737:chemistry*; D006801:Humans; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein; D013816:Thermodynamics
D006657:Histones