title: CdnL, a member of the large CarD-like family of bacterial proteins, is vital for Myxococcus xanthus and differs functionally from the global transcriptional regulator CarD.
abstract: CarD, a global transcriptional regulator in Myxococcus xanthus, interacts with CarG via CarDNter, its N-terminal domain, and with DNA via a eukaryotic HMGA-type C-terminal domain. Genomic analysis reveals a large number of standalone proteins resembling CarDNter. These constitute, together with the RNA polymerase (RNAP) interacting domain, RID, of transcription-repair coupling factors, the CarD_TRCF protein family. We show that one such CarDNter-like protein, M. xanthus CdnL, cannot functionally substitute CarDNter (or vice versa) nor interact with CarG. Unlike CarD, CdnL is vital for growth, and lethality due to its absence is not rescued by homologs from various other bacteria. In mycobacteria, with no endogenous DksA, the function of the CdnL homolog mirrors that of Escherichia coli DksA. Our finding that CdnL, like DksA, is indispensable in M. xanthus implies that they are not functionally redundant. Cells are normal on CdnL overexpression, but divide aberrantly on CdnL depletion. CdnL localizes to the nucleoid, suggesting piggyback recruitment by factors such as RNAP, which we show interacts with CdnL, CarDNter and RID. Our study highlights a complex network of interactions involving these factors and RNAP, and points to a vital role for M. xanthus CdnL in an essential DNA transaction that affects cell division.
authors.affiliation: Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, Spain.
authors.forename: Diana
authors.initials: D
authors.lastname: García-Moreno
authors.forename: Javier
authors.initials: J
authors.lastname: Abellón-Ruiz
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Heras
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Murillo
authors.forename: S
authors.initials: S
authors.lastname: Padmanabhan
authors.forename: Montserrat
authors.initials: M
authors.lastname: Elías-Arnanz
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D001483:Base Sequence; D002455:Cell Division; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D017353:Gene Deletion; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016941:Myxococcus xanthus / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; C100589:CarD protein, Myxococcus xanthus; D015534:Trans-Activators; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases