Involved in the nicotine degradation. Catalyzes the cleavage of 6-hydroxy-3-succinoylpyridine (HSP) by incorporation of oxygen at the 3-position to produce to 2,5-dihydroxypyridine (DHP) and succinic semialdehyde. 4-(6-hydroxypyridin-3-yl)-4-oxobutanoate + 2 H(+) + 2 NADH + O2 = 2,5-dihydroxypyridine + H2O + 2 NAD(+) + succinate semialdehyde Binds 1 FAD per subunit. Inhibited by Cu(2+) and Zn(2+). kcat is 2 sec(-1). Optimum pH is 8. At pH below 7.0 or above 9.0, there is substantial loss of activity. Optimum temperature is 25 degrees Celsius. The enzyme activity measured at 5 degrees Celsius is maintained up to 25 degrees Celsius but is lost quickly at higher temperatures. Alkaloid degradation; nicotine degradation. Homodimer. Cells lacking this gene are not able to grow in nicotine medium. The catalytic efficiency of HspB is higher than that of HspA.