title: Characterization of a novel signal transducer element intrinsic to class IIIa/b adenylate cyclases and guanylate cyclases.
abstract: Adenylate cyclases (ACs) are signaling proteins that produce the second messenger cAMP. Class III ACs comprise four groups (class IIIa-d) of which class IIIa and IIIb ACs have been identified in bacteria and eukaryotes. Many class IIIa ACs are anchored to membranes via hexahelical domains. In eukaryotic ACs, membrane anchors are well conserved, suggesting that this region possesses important functional characteristics that are as yet unknown. To address this question, we replaced the hexahelical membrane anchor of the mycobacterial AC Rv1625c with the hexahelical quorum-sensing receptor from Legionella, LqsS. Using this chimera, we identified a novel 19-amino-acid cyclase transducer element (CTE) located N-terminally to the catalytic domain that links receptor stimulation to effector activation. Coupling of the receptor to the AC was possible at several positions distal to the membrane exit, resulting in stimulatory or inhibitory responses to the ligand Legionella autoinducer-1. In contrast, on the AC effector side functional coupling was only successful when starting with the CTE. Bioinformatics approaches established that distinct CTEs are widely present in class IIIa and IIIb ACs and in vertebrate guanylate cyclases. The data suggest that membrane-delimited receiver domains transduce regulatory signals to the downstream catalytic domains in an engineered AC model system. This may suggest a previously unknown mechanism for cellular cAMP regulation.
authors.affiliation: Pharmazeutisches Institut der Universität Tübingen, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Ziegler
authors.affiliation: Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Bassler
authors.affiliation: Pharmazeutisches Institut der Universität Tübingen, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Beltz
authors.affiliation: Pharmazeutisches Institut der Universität Tübingen, Germany.
authors.forename: Anita
authors.initials: A
authors.lastname: Schultz
authors.affiliation: Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
authors.forename: Andrei N
authors.initials: AN
authors.lastname: Lupas
authors.affiliation: Pharmazeutisches Institut der Universität Tübingen, Germany.
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Schultz
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D001120:Arginine / Q000378:metabolism; D019295:Computational Biology; D006162:Guanylate Cyclase / Q000378:metabolism*; D053038:Quorum Sensing; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D011956:Receptors, Cell Surface; D001120:Arginine; D000262:Adenylyl Cyclases; D006162:Guanylate Cyclase
keywords: 
  Legionella
  ; cyclic AMP; quorum-sensing; receptor regulation; signal transduction