Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Forty-nine bacterial strains representing five species known to interact with human plasminogen were tested for the ability to bind the two major human plasminogen activators, t-PA and urokinase. The bacterial species tested included Haemophilus influenzae, Neisseria meningitidis, Streptococcus pyogenes, Streptococcus equisimilis and human group G streptococci. All N. meningitidis and 11 of 14 H. influenzae strains displayed substantial binding of t-PA with values in the range of 20-46%. On the contrary, none of the streptococcal strains bound significant amounts of tPA. With urokinase no binding could be found for any of the bacterial species tested. Scatchard analysis with a selected H. influenzae strain (HI23354) demonstrated 10,000 receptors per bacterium for t-PA with a Kd value of about 20 nmol l-1. The corresponding values with a selected N. meningitidis strain (Mo 52) was 8500 receptors per bacterium and 70 nmol l-1. t-PA binding could be reduced about 40% by the addition of 10 mmol l-1 of the lysine analogue epsilon-aminocaproic acd (EACA) whereas no inhibitory effect could be demonstrated with arginine. Addition of 2 mumol l-1 of plasminogen which is enough to occupy all bacterial sites for plasminogen did not interfere with the t-PA binding, suggesting that the receptors for t-PA and plasminogen are distinct. Using very high plasminogen concentrations however, t-PA binding could be reduced by about 50% possibly due to an interaction between t-PA and plasminogen in the fluid phase. Our results demonstrate the occurrence of a previously unknown type of bacterial receptor that is capable of specifically binding t-PA.
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PMID:Binding of tissue-type plasminogen activator (t-PA) to Neisseria meningitidis and Haemophilus influenzae. 780 68

Plasminogen binding proteins have been described both for Gram positive and Gram negative bacteria. In the present work we describe the purification and characterization of a plasminogen binding protein from Haemophilus influenzae (strain HI-23459). Bacteria were sonicated in order to solubilize plasminogen-binding proteins. The supernatant was subjected to affinity chromatography on plasminogen kringle-4 fragment bound to Sepharose 4B and subsequently processed by ion-exchange chromatography on DEAE-Sepharose CL-6B. Characterization of the protein by SDS-PAGE displayed a single band with a molecular mass of about 55,000, both prior to and after reduction. The purified protein stimulates tPA (tissue plasminogen activator) catalysed plasminogen activation by a factor of approximately 300, mainly due to a decrease in K(m). Antibodies were raised in rabbits and used in quantitative and qualitative analysis. However, using a FITC-conjugate we failed to demonstrate the presence of the purified protein on the surface of intact bacteria. The corresponding gene was isolated from a lambda EMBL3 phage library prepared from chromosomal DNA from the same H. influenzae strain, using an oligonucleotide probe based on the NH2-terminal amino acid sequence. An open reading frame corresponding to 472 amino acid was found. The amino acid sequence of the translated gene demonstrates 97% identity with the recently published sequence from aspartate ammonia lyase (aspartase) from H. influenzae. Enzymatic analysis of the purified protein revealed a high aspartase activity.
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PMID:Purification and characterisation of a plasminogen-binding protein from Haemophilus influenzae. Sequence determination reveals identity with aspartase. 909 5