HUMAN HISTONE GENE ORGANIZATION - NONREGULAR ARRANGEMENT WITHIN A LARGE CLUSTER

We have previously located the genes of the five human main type H1 ge nes and the gene encoding the testicular subtype H1t to the region 21. 1 to 22.2 on the short arm of chromosome 6. To investigate the organiz ation of the histone genes in this region, we isolated two YACs from a human YAC library by PCR screening with primers specific for histone H1.1. This screen revealed two YAC clones. YAC Y23 (corresponding to I CRFy901D1223) contains an insert of about 480 kb, whereas the smaller YAC 4A (corresponding to ICRFy900C104) spans about 340 kb and is compl etely covered by YAC Y23. We have subcloned the YAC inserts in cosmids , determined the linear orientation of the cosmids by cosmid walking, and constructed a restriction map of the entire region by mapping the individual cosmids using partial digests and hybridization with labele d oligonucleotides complementary to the cos site of the vector. Hybrid ization analysis, subcloning, restriction mapping, and sequencing reve aled that most of the previously isolated phage and cosmid clones cont aining histone genes are part of this YAC including the clones contain ing the four human main type H1 histone genes H1.1 to H1.4, the H1t ge ne, and core histone genes. Thirty-five histone genes map within 260 k b of the YAC Y23 insert. Ail newly identified histone genes were seque nced, and the sequences were deposited with the EMBL nucleotide sequen ce database. The histone H1.5 gene is not part of this region, and we therefore conclude that the H1.5 gene and the associated core histone genes form a separate subcluster within this chromosomal region. (C) 1 997 Academic Press.