The Histones of Rainbow Trout Erythrocytes Include an Erythrocyte-Specific Histone

Abstract

The erythrocyte histones of rainbow trout were compared with those of goose by polyacrylamide gel electrophoresis. A band analogous to goose erythrocyte-specific histone V, but not identical in relative mobility or quantity, was found to be a component of trout erythrocyte histone. A similar component was also found in carp erythrocyte histone, but it was absent from trout liver histone. To reveal this band clearly, it was advantageous to displace the histone III monomer by oxidation. To verify the character of this protein, each of the main erythrocyte histones of trout were purified by chromatography on Amberlite CG-50, eluted with guanidinium chloride, and then further purified by exclusion chromatography on Bio-Gel P-60. Amino acid compositions of corresponding trout and goose histones, including that of the erythrocyte-specific histone, were sufficiently similar to establish their analogous identities. In general, the chromatographic and electrophoretic properties of histones I, IIb1, IIb2, and V from trout differed more from those of goose, than did their gross amino acid compositions. Comprehensive fractionation and characterization is necessary to extablish identities of corresponding histone fractions, An extensive quantitative variability was found among erythrocyte-specific histones of fish. This must be reconciled with hypothetical roles for this histone in erythropoiesis.

Binding of histones H1 and H5 and their globular domains to four-way junction DNA.

“…These previous results and the demonstration by Bianchi et al (10) (14,15). It is similar in sequence and structure to H1 but has multiple lysine-to-arginine substitutions relative to H1.…”

“…4WJ DNA is the core structure of cruciform DNA (which may extrude from palindromic sequences under torsional stress) and the Holiday junction (which forms during homologous recombination). Stable 4WJs can also be formed by annealing appropriately chosen oligonucleotides in vitro (9), and thus provide a convenient model system to study proteins which might interact specifically with this type of DNA structure.These previous results and the demonstration by Bianchi et al (10) (14,15). It is similar in sequence and structure to H1 but has multiple lysine-to-arginine substitutions relative to H1.…”

A survey of H10‐ and H5‐like protein structure and distribution in higher and lower eukaryotes

“…However, the abundance of HI" varied considerably from virtually none in the rabbit liver to the maximum that we are aware of, where about a third of H1 is replaced by HI", in mouse liver [22]. This resembles the situation with variable amounts of H5 in the nucleated erythrocytes of fishes and birds [4]. The question of whether H1"-or H5-like proteins occur in lower eukaryotes was addressed by a search in a crustacean, two fungi and a plant.…”

“…This contrasts with HI" which has a much smaller arginine content and occurs in most or all tissues, replacing only a minority of H1 there. This suggestion may be incorrect, however, for putative H5 proteins have been isolated from the nucleated erythrocytes of various non-avian vertebrates such as fish [4] which have chromatographic properties and total amino acid contents which more closely resemble those of mammalian Hl". For instance, they have less arginine than does avian H5, though still more than does HI", and their abundance is less than that of avian H5 (see [4]).…”

“…This suggestion may be incorrect, however, for putative H5 proteins have been isolated from the nucleated erythrocytes of various non-avian vertebrates such as fish [4] which have chromatographic properties and total amino acid contents which more closely resemble those of mammalian Hl". For instance, they have less arginine than does avian H5, though still more than does HI", and their abundance is less than that of avian H5 (see [4]). More significantly, there are examples of putative H5-or HI"-like proteins which are not restricted to the nucleated erythrocyte of a reptile [5] and an amphibian [6], neither of which has a histone which is specific to the erythrocyte.…”