Stabilizes TBP binding to an archaeal box-A promoter. Also responsible for recruiting RNA polymerase II to the pre-initiation complex (DNA-TBP-TFIIB). (Microbial infection) At least 4-fold induced following infection by Sulfolobus turreted icosahedral virus 1 (STIV-1) in strain 2-2-12. Strain 2-2-12 is a substrain of P2 that is highly susceptible to infection by Sulfolobus turreted icosahedral virus 1 (STIV-1). Belongs to the TFIIB family.