Self-polymerization of archaeal RadA protein into long and fine helical filaments

The Archaeal protein RadA, a RecA/Rad51 homolog, is able to promote pairing and exchange of DNA strands with homologous sequences. Here, we have expressed, purified, and crystallized the catalytically active RadA protein from Sulfolobus solfataricus (Sso). Preliminary X-ray analysis indicated that Sso RadA protein likely forms helical filament in protein crystals. Using atomic force microscopy with a carbon nanotube (CNT) tip for high-resolution imaging, we demonstrated that Sso RadA protein indeed forms fine helical filaments up to 1 microm in length ( approximately 10nm pitch) in the absence of DNA and nucleotide cofactor. We also observed that Sso RadA protein helical filament could dissemble upon incubation with ssDNA, and then the proteins associate with ssDNA to form nucleoprotein filament.     

Effects of olmesartan on arterial stiffness in rats with chronic renal failure

ABSTRACT: BACKGROUND: It has been suggested that the antioxidant properties of olmesartan (OLM), an angiotensin II type 1 receptor (AT1R) blocker, contribute to renal protection rather than blood pressure lowering effects despite the fact that causal relationships between hypertension and renal artery disease exist. This study aimed to examine the hypothesis whether the antioxidative activities of OLM were correlated to arterial stiffness, reactive oxygen species and advanced glycation end products (AGEs) formation in rats with chronic renal failure (CRF). METHODS: CRF rats were induced by 5/6 nephrectomy and randomly assigned to an OLM (10 mg/day) group or a control group. Hemodynamic states, oxidative stress, renal function and AGEs were measured after 8 weeks of OLM treatment. RESULTS: All the hemodynamic derangements associated with renal and cardiovascular dysfunctions were abrogated in CRF rats receiving OLM. Decreased cardiac output was normalized compared to control (p <0.05). Mean aortic pressure, total peripheral resistance and left ventricular weight/body weight ratio were reduced by 21.6 % (p <0.05), 28.2 % (p <0.05) and 27.2 % ((p <0.05). OLM also showed beneficial effects on the oscillatory components of the ventricular after-load, including 39 % reduction in aortic characteristic impedance (p < 0.05), 75.3 % increase in aortic compliance (p <0.05) and 50.3 % increase in wave transit time (p < 0.05). These results implied that OLM attenuated the increased systolic load of the left ventricle and prevented cardiac hypertrophy in CRF rats. Improved renal function was also reflected by increases in the clearances of BUN (28.7 %) and serum creatinine (SCr, 38.8 %). In addition to these functional improvements, OLM specifically reduced the levels of malondialdehyde (MDA) equivalents in aorta and serum by 14.3 % and 25.1 %, as well as the amount of AGEs in the aortic wall by 32 % (p < 0.05) of CRF rats. CONCLUSION: OLM treatment could ameliorate arterial stiffness in CRF rats with concomitant inhibition of MDA and AGEs levels through the reduction of oxidative stress in aortic wall.