The Shiga toxin (Stx)-encoding bacteriophage 933W contains an open reading frame, stk, with amino acid sequence similarity to the catalytic domain of eukaryotic serine/threonine (Ser/Thr) protein kinases (PKs). Eukaryotic PKs are related by a common catalytic domain, consisting of invariant and nearly invariant residues necessary for ATP binding and phosphotransfer. We demonstrate that rather t...

Streptokinase (STK) is clinically used world-wide as a thrombolytic agent to treat patients with acute myocardial infarction, deep vein thrombosis, arterial thrombosis and embolism [1-3]. The structure of STK consists of a 414 amino acids polypeptide chain with a molecular mass of 47 kDa. The protein exhibits its maximum activity at a pH of approximately 7.5 and its pI is 4.7. Most of the nativ...

background : immunogenicity of streptokinase (stk), as a thrombolytic drug, have limited its clinical use. elimination of the amino acid residues that are responsible for immunogenicity while don’t affect the bioactivity of stk is worthy. recently, we modified the stk through elimination of 42 amino acids from its’ c-terminal and assessed its bioactivity in vitro . objective : in this study, bi...

Streptococcus suis serotype 2 is an important swine pathogen and an emerging zoonotic agent that causes severe infections. Recent studies have reported a eukaryotic-like Ser/Thr protein kinase (STK) gene and characterized its role in the growth and virulence of different S. suis 2 strains. In the present study, phosphoproteomic analysis was adopted to identify substrates of the STK protein. Sev...

We cloned the streptokinase (STK) gene of Streptococcus equisimilis in an expression vector of Escherichia coli to overexpress the profibrinolytic protein under the control of a tac promoter. Almost all the recombinant STK was exported to the periplasmic space and recovered after gentle lysozyme digestion of induced cells. The periplasmic fraction was chromatographed on DEAE Sepharose followed ...

BACKGROUND Serine/threonine kinases are involved in gene regulation and signal transduction in prokaryotes and eukaryotes. Here, we investigated the role of the serine/threonine kinase Stk in the opportunistic pathogen Staphylococcus epidermidis. METHODOLOGY/PRINCIPAL FINDINGS We constructed an isogenic stk mutant of a biofilm-forming clinical S. epidermidis isolate. Presence of stk was impor...

Recently we cloned a novel receptor tyrosine kinase, STK. STK belongs to the hepatocyte growth factor receptor family and was identified as the receptor for macrophage-stimulating protein (MSP). STK is expressed on a restricted, macrophage population such as peritoneal macrophages, but not on mononuclear phagocytes of peripheral blood, bone marrow, or alveoli. Using an anti-STK monoclonal antib...

STK, a new member of the hepatocyte growth factor receptor family, is the receptor for macrophage-stimulating protein (MSP), which acts on murine resident peritoneal macrophages. We established polyclonal and monoclonal antibodies against STK and characterized the structure of STK protein and STK expression on cells of the mononuclear phagocyte system. Western blotting showed that the STK trans...

Genes encoding one or more Ser/Thr protein kinases have been identified recently in many bacteria, including one (stk) in the human pathogen Streptococcus pyogenes (group A streptococcus [GAS]). We report that in GAS, stk is required to produce disease in a murine myositis model of infection. Using microarray and quantitative reverse transcription-PCR (qRT-PCR) studies, we found that Stk activa...

Infection of erythroid progenitor cells by Friend spleen focus-forming virus (SFFV) leads to acute erythroid hyperplasia and eventually to erythroleukemia in susceptible strains of mice. The viral envelope protein, SFFV gp55, forms a complex with the erythropoietin receptor (EpoR) and a short form of the receptor tyrosine kinase Stk (sf-Stk), activating both and inducing Epo-independent prolife...