RESUMO
The CO2-concentrating mechanism (CCM) has evolved to improve the efficiency of photosynthesis in autotrophic cyanobacteria. CmpR, a LysR-type transcriptional regulator (LTTR) from Synechococcus elongatus PCC 7942, was found to regulate CCM-related genes under low-CO2 conditions. Here, the dimeric structure of the effector-binding domain of CmpR (CmpR-EBD) in complex with the co-activator ribulose 1,5-bisphosphate (RuBP) is reported at 2.15â Å resolution. One RuBP molecule binds to the inter-domain cleft between the two subunits of the CmpR-EBD dimer. Structural comparison combined with sequence analyses demonstrated that CmpR-EBD has an overall structure similar to those of LTTRs of known structure, but possesses a distinctly different effector-binding pattern.
Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Ribulose-Bifosfato Carboxilase/química , Ribulose-Bifosfato Carboxilase/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Sítios de Ligação/fisiologia , Cristalização , Proteínas de Ligação a DNA/genética , Estrutura Secundária de Proteína , Ribulose-Bifosfato Carboxilase/genéticaRESUMO
Ultra-small gold nanoclusters (Au NCs) are highly promising materials for tumor imaging and therapy because of their low toxicity, intrinsic fluorescence, and the availability of multifunctional groups for covalent linkage of diverse bioactive molecules. Au NCs stabilized by bovine serum albumin (BSA) were prepared via an improved "green" synthetic routine. To ameliorate the selective affinity of Au NCs for high folate receptor (FR) expressing tumors, folic acid (FA) was immobilized on the surface of Au NCs. Subsequently, a near-infrared (NIR) fluorescent dye MPA was conjugated with Au-FA NCs for in vitro and in vivo fluorescence imaging. Similarly, Doxorubicin (DOX), a widely used clinical anticancer drug, was also conjugated to the folate-modified Au NCs to form a prodrug (Au-FA-DOX). Cellular and in vivo acute toxicity studies demonstrated the low toxicity of the Au-FA-MPA to normal cells and tissues. Additionally, in vitro and in vivo study of the dynamic behavior and targeting ability of Au-FA-MPA to different tumors validated the high selective affinity of Au-FA-MPA to FR positive tumors. With regard to the Au-FA-DOX, high anti-tumor activity was displayed by this pro-drug due to the FR mediated uptake. Herein, all of the results supported the potential of using ligand-modified Au NCs for tumor imaging and targeted therapy.
Assuntos
Corantes Fluorescentes/química , Ácido Fólico/química , Ouro/química , Nanopartículas Metálicas/química , Neoplasias/diagnóstico , Animais , Antibióticos Antineoplásicos/farmacocinética , Antibióticos Antineoplásicos/uso terapêutico , Antibióticos Antineoplásicos/toxicidade , Apoptose/efeitos dos fármacos , Bovinos , Linhagem Celular Tumoral , Doxorrubicina/farmacocinética , Doxorrubicina/uso terapêutico , Doxorrubicina/toxicidade , Receptor 1 de Folato/química , Receptor 1 de Folato/metabolismo , Células HCT116 , Células Hep G2 , Humanos , Camundongos , Camundongos Nus , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Soroalbumina Bovina/química , Espectroscopia de Luz Próxima ao Infravermelho , Distribuição TecidualRESUMO
PURPOSE: A novel near infrared fluorescent probe, L-methyl-methionine (Met)-ICG-Der-02, was synthesized and characterized for in vivo imaging of tumors and early diagnosis of cancers. METHOD: Met was conjugated with ICG-Der-02 dye through the amide bond function by ethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide catalysis chemistry. Met-ICG-Der-02 probe uptake was evaluated on PC3, MDA-MB-231, and human embryonic lung fibroblast cell lines. The dynamics of Met-ICG-Der-02 was investigated in athymic nude mice prior to evaluation of the probe targeting capability in prostate and breast cancer models. RESULTS: Met-ICG-Der-02 was successfully synthesized. Cell experiments demonstrated excellent cellular uptake of Met-ICG-Der-02 on cancer cell lines without cytotoxicity. Optical imaging showed a distinguishable fluorescence signal in the tumor area at 2 h while maximal tumor-to-normal tissue contrast ratio was at 12 h Met-ICG-Der-02 post-injection. Additionally, dynamic study of the probe indicated intestinal and liver-kidney clearance pathways. CONCLUSION: Met-ICG-Der-02 probe is a promising optical imaging agent for tumor diagnosis, especially in their early stage.