7beta-hydroxysteroid dehydrogenase that catalyzes the reduction of the 7-oxo group of 7-oxosteroids, such as 3alpha,12alpha-dihydroxy-7-oxo-5beta-cholanate, 7-oxolithocholate, 7,12-dioxo-lithocholate and dehydrocholate, to the corresponding 7beta-hydroxysteroids. Is also able to catalyze the reverse oxidation reactions. Together with 7alpha-HSDH encoded in the adjacent gene, is likely involved in the epimerization of the hydroxy group at C-7 of primary bile acids through 7-keto bile acid intermediates. a 7beta-hydroxysteroid + NADP(+) = a 7-oxosteroid + H(+) + NADPH NADP(+) + ursocholate = 3alpha,12alpha-dihydroxy-7-oxo-5beta-cholanate + H(+) + NADPH 7-oxolithocholate + H(+) + NADPH = NADP(+) + ursodeoxycholate 3alpha,7beta-dihydroxy-12-oxo-5beta-cholan-24-oate + NADP(+) = 7,12-dioxo-lithocholate + H(+) + NADPH 7beta-hydroxy-3,12-dioxo-5beta-cholan-24-oate + NADP(+) = dehydrocholate + H(+) + NADPH kcat is 407000 sec(-1) for the oxidation of ursocholate. kcat is 203000 sec(-1) for the reduction of 3alpha,12alpha-dihydroxy-7-oxo-5beta-cholanate. kcat is 430000 sec(-1) for the oxidation of ursodeoxycholate. kcat is 639000 sec(-1) for the reduction of 7-oxolithocholate. kcat is 413000 sec(-1) for the reduction of 7,12-dioxo-lithocholate. kcat is 146000 sec(-1) for the reduction of dehydrocholate. Shows a maximum of activity at pH 8.5 in the oxidation of ursocholate, and between pH 7.0 and 8.0 when tested in the reduction reaction of 3alpha,12alpha-dihydroxy-7-oxo-5beta-cholanate, with a gradual drop on the alkaline side and a sharp drop on the acidic side. Optimum temperature is 40 degrees Celsius. No activity is detected above 60 degrees Celsius. Homodimer. Induced by bile acids, when grown in the presence of deoxycholate or chenodeoxycholate. Could be a promising candidate for further applications in the epimerization reaction of bile acids at the C-7 position and thus may be used as a biocatalyst for the synthesis of bile acids derivatives of pharmacological interest. Belongs to the short-chain dehydrogenases/reductases (SDR) family.