Cloning the genes and DNA binding properties of High Mobility Group B1 (HMGB1) proteins from the human blood flukes Schistosoma mansoni and Schistosoma japonicum

• Published in: Gene 2006-08, Vol.377, p.33-45
• Main Authors: de Oliveira, Francisco Meirelles Bastos, de Abreu da Silva, Isabel Caetano, Rumjanek, Franklin David, Dias-Neto, Emmanuel, Guimarães, Pedro Edson Moreira, Verjovski-Almeida, Sergio, Štros, Michal, Fantappié, Marcelo Rosado
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Cloning, Molecular; DNA bending; DNA binding; DNA supercoiling; DNA, Complementary - genetics; DNA, Helminth - chemistry; DNA, Helminth - genetics; DNA, Helminth - metabolism; DNA, Superhelical - chemistry; DNA, Superhelical - genetics; DNA, Superhelical - metabolism; Genes, Helminth; Genomic structure; Helminth Proteins - genetics; Helminth Proteins - metabolism; HMGB1 Protein - genetics; HMGB1 Protein - metabolism; Humans; Molecular Sequence Data; Nucleic Acid Conformation; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; S. japonicum HMGB1 protein; S. mansoni HMGB1 protein; Schistosoma; Schistosoma japonicum; Schistosoma japonicum - genetics; Schistosoma japonicum - metabolism; Schistosoma japonicum - pathogenicity; Schistosoma mansoni; Schistosoma mansoni - genetics; Schistosoma mansoni - metabolism; Schistosoma mansoni - pathogenicity; Sequence Homology, Amino Acid; Trematoda
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/j.gene.2006.03.001

The parasitic helminth Schistosoma mansoni contains three HMGB proteins, HMGB1, HMGB2 and HMGB3, of primary amino acid sequences highly similar to vertebrate proteins. In this report we describe the characterization of the HMGB1 proteins and their genes from S. mansoni and Schistosoma japonicum. The deduced amino acid sequences of HMGB1 proteins from both schistosome species are identical, and comprise 176 residues. The proteins contain the two evolutionarily highly conserved HMG-box domains, A and B, exhibiting 60% similarity to mammalian HMGB1. Unlike the human HMGB1 which contains an unbroken run of 30 glutamic or aspartic residues, the SmHMGB1 or SjHMGB1 proteins possess unusually short acidic C-terminal tails (5 acidic residues interrupted by 2 serines). Southern hybridization and DNA sequencing revealed a single copy HMGB1 gene, composed of 3 exons and two introns, in S. mansoni. The exon/intron boundaries are identical to those of the human HMGB1 gene, with the exception that the second exon of the SmHMGB1 gene which is not split into two exons as in the human HMGB1 gene. RNA blot analysis revealed that the SmHMGB1 gene is constitutively expressed in similar levels both in male and female worms. The single-sized mRNA for SmHMGB1 is consistent with the size derived from the cDNA. Although DNA binding properties of SmHMGB1 (or SjHMGB1) protein seem to be similar to those previously reported with human HMGB1, i.e., preferential binding to supercoiled DNA over linear DNA, specific recognition of DNA four-way junctions, DNA-induced supercoiling in the presence of topoisomerase I, and DNA bending, we have observed two important differences relative to those observed with the human HMGB1: (i) the inability of the isolated SmHMGB1 domain A to bend DNA (as revealed by T4 ligase-mediated circularization assay), and (ii) higher DNA supercoiling and bending potential of the SmHMGB1 protein as compared to its human counterpart. The latter finding may indicate that the long acidic C-tail of human HMGB1 has much stronger repressive role on DNA bending or DNA supercoiling by topoisomerase I at physiological ionic strength than the short C-tail of the SmHMGB1 protein. Considering the important role of HMGB1 in DNA replication, transcription, recombination, and in particularly, the mediation of inflammation responses in mammalian cells, further studies on schistosome HMGB proteins may provide valuable information related to schistosomiasis, where inflammation plays a