Involved in thaumarchaeal hydroxypropionate/hydroxybutyrate (HP/HB) cycle, a modified version of the autotrophic HP/HB cycle of Crenarchaeota. Catalyzes the formation of 3-hydroxypropionyl-CoA, ADP and phosphate from 3-hydroxypropionate, coenzyme A (CoA) and ATP. Can also use 4-hydroxybutyrate, propionate and butyrate, with poor catalytic efficiency. 3-hydroxypropanoate + ATP + CoA = 3-hydroxypropanoyl-CoA + ADP + phosphate No activity with Ni(2+), Co(2+) and Ca(2+). In the N-terminal section; belongs to the acetate CoA ligase beta subunit family. In the C-terminal section; belongs to the acetate CoA ligase alpha subunit family.