[Isolation and characteristics of catalytic antibodies to DNA in systemic lupus erythematosis]. / Vydelenie i kharakteristika kataliticheskikh antitel k DNK pri sistemnoi krasnoi volchanke.

A method for purifying DNA-specific catalytic antibodies based on affinity chromatography on protein A Sepharose and on both modified and non-modified DNA-cellulose as well as HPLC has been developed. The elution conditions with high yields of DNA-hydrolyzing activity of antibodies have been optimized. The biochemical and immunological properties of catalytic antibodies have been examined. The kinetic parameters of the enzyme interaction with an oligonucleotide substrate have been determined. The influence of effectors on DNA hydrolysis by antibodies has been investigated.

DNA hydrolyzing autoantibodies.

A DNA-nicking activity was detected in the sera of patients with various autoimmune pathologies and was shown to be a property of autoantibodies. The DNA hydrolyzing activity, which was purified by affinity and high-performance liquid chromatography, corresponded in size to immunoglobulin M (IgM) and IgG and had a positive response to antibodies to human IgG. The DNA hydrolyzing autoantibodies were stable to acid shock and yielded a DNA degradation pattern that was different from that of deoxyribonuclease (DNase) I and blood DNase.

Identification of a sequence-specific protein binding the 5'-transcribed spacer of rat ribosomal genes.

A novel 85-kD protein factor which interacts specifically with the 5'-transcribed spacer of rat ribosomal genes was identified using the gel mobility shift, DNase I protection and UV-crosslinking techniques. The binding site of the factor is located inside the 36 bp Alul-HindIII fragment of transcribed spacer, most probably in the region +94 to +115 with respect to the transcription initiation site. Factors giving very similar gel mobility shift patterns were also found in mouse and human cell extracts. Sequences resembling the binding site of this factor were revealed in corresponding regions of mouse and human ribosomal genes. The biological function of FTS remains to be elucidated.

[Protein factors specifically binding to the regulatory elements of non-transcribed spacer of rat ribosomal genes]. / Belkovye faktory, spetsificheski sviazyvaiushchiesia s reguliatornymi élementami netranskribiruemogo speisera ribosomnykh genov krysy.

Mouse, rat and human protein factors recognizing regulatory elements of nontranscribed spacer of rat ribosomal genes were studied by gel retardation assay. Protein factors bind specifically to the DNA fragments containing the core promoter sequence of RNA-polymerase I, to "spacer" promoter and to a putative enhancer sequence. Factors of mouse, rat and human nuclear extracts that recognize the region containing the core promoter sequence have similar molecular masses and are not identical to the previously described protein factor TIF-1B. Two factors that bind the "spacer" promoter region differ from the factors of the core promoter. "Spacer" promoter factors of mouse and rat nuclear extracts are probably identical, but differ from those of human extract. Protein factors, recognizing the putative enhancer region of rat and human extracts are alike but were not detected in mouse extract. Regions of nontranscribed spacer containing dispersed and tandem repeats do not bind any specific protein factors.

Nucleotide sequence analysis of the spacer regions flanking the rat rRNA transcription unit and identification of repetitive elements.

We investigated the organization of the rat rDNA non-transcribed spacer (NTS) by determining the sequence of large NTS segments located upstream (2501 bp) and downstream (4025 bp) from the rRNA transcription unit. We identified four B2-like and two ID mobile elements. They may be grouped in three pairs with the members of each pair located in the upstream and downstream NTS. The ID sequences are identical to the consensus sequence, while the pairs of B2-like elements show 85% and 50/65% homology to the consensus B2 sequence. The proximal part of the downstream NTS contains a region of widely diverged SalI tandem repeats. A considerable part of the analyzed upstream and downstream NTS sequences is constituted by different types of simple sequences and long poly(purine) X poly(pyrimidine) tracts. These data show that the rat rDNA NTS regions flanking the rRNA transcription unit are characterized by a combination of short interspersed (B2-superfamily) and various simple sequences.