Comparative characteristics of physico-chemical and regulating properties of aspartate kinases from three species of cyanobacteria

Aspartokinases have been isolated from the cell-free extracts of Plectonema boryanum, Anabaena variabilis and Synechococcus cedrorum. Their physico-chemical characteristics and peculiarities of retroregulation by amino acids were studied. It has been shown that in P. boryanum cells aspartokinase reaction is catalyzed by only one enzyme, which is similar to the previously described bacterial origin enzymes. Three izoenzymes, which differ in their main properties and amino acids-effectors, have been founded in the cells of A. variabilis. One enzyme with aspartokinase activity, which differs from other cyanobacteria enzymes in some physico-chemical features has been founded in the cells of S. cedrorum.     

The nucleotide sequence of the rep gene of cyanobacterial plasmid pSM1

The nucleotide sequence was established for the rep gene of plasmid pSM1 isolated from cyanobacterium Plectonema boryanum CALU 465. Both nucleotide sequence and the encoded amino acid sequences showed 98% homology to the corresponding sequences of small plasmids pPF1, pGL3, pPBS1, pBLX, and pPB1. An active center was identified in the replicative protein sequences.     

The Nucleotide Sequence of the rep Gene of Cyanobacterial Plasmid pSM1

The nucleotide sequence was established for the rep gene of plasmid pSM1 isolated from cyanobacteriumPlectonema boryanum CALU 465. Both nucleotide sequence and the encoded amino acid sequences showed 98% homology to the corresponding sequences of small plasmids pPF1, pGL3, pPBS1, pBLX, and pPB1. An active center was identified in the replicative protein sequences.     

2 site-specific endonucleases of the cyanobacterium Nostoc linckia]

Two restrictases Nli387/7 I and Nli387/7 II have been isolated from cyanobacterium Nostoc linckia using chromatography on phosphocellulose, "Mono Q" column, and heparin sepharose 4B. The preparations are described by the method of electrophoresis in polyacrylamide gel under denaturing conditions. Catalytic properties of restrictases are determined: optimal pH of the action--9.0--9.5, optimal concentration of Na+--5 mM, that of Mg2+--6 mM, optimal temperature--37 degrees C. The isolated enzymes are isoschizomers of restrictases avaI and AvaII. The point of cutting is determined for enzyme Nli387/7 I. It is shown that restrictase Nli387/7 I is a false isoschizomer Ava I.     

Construction of vector plasmids for the Plectonema boryanum cyanobacterium and creation,on such basis,of the vector-host system

The plasmid composition of the Plectonema boryanum Gom. Cyanobacterium, strain CALU 465, was analyzed. A small pSM1 plasmid, size 1.5, was chosen for genetic engineering. The physical map, constructed for the plasmid, was used to create the pSTS series, i.e. vector construction for the P. boryanum cyanobacterium. A method was selected and tested for the introduction of the vector into host cells. The needed orientation of pSM1 cyanobacterium plasmid within the vector as well as a possible role of its separate elements in inheriting the construction by host were defined.