P_IISignal Transduction Proteins, Pivotal Players in Microbial Nitrogen Control

Abstract

SUMMARY The PII family of signal transduction proteins are among the most widely distributed signal proteins in the bacterial world. First identified in 1969 as a component of the glutamine synthetase regulatory apparatus, PII proteins have since been recognized as playing a pivotal role in control of prokaryotic nitrogen metabolism. More recently, members of the family have been found in higher plants, where they also potentially play a role in nitrogen control. The PII proteins can function in the regulation of both gene transcription, by modulating the activity of regulatory proteins, and the catalytic activity of enzymes involved in nitrogen metabolism. There is also emerging evidence that they may regulate the activity of proteins required for transport of nitrogen compounds into the cell. In this review we discuss the history of the PII proteins, their structures and biochemistry, and their distribution and functions in prokaryotes. We survey data emerging from bacterial genome sequences and consider other likely or potential targets for control by PII proteins.

Functional organization of a single nif cluster in the mesophilic archaeon Methanosarcina mazei strain Gö1

“…Additional open reading frames in the adjacent regions on either side of the cluster have been tentatively identified as a flavine-containing oxidoreductase (upstream of nifH) and a periplasmic molybdate binding protein plus a molybdenum transporter (downstream of nifN). The order of the M. mazei nitrogen fixation genes is the same as in other diazotrophic methanogenic archaea and differs from most bacterial nif gene clusters in that the two nifI genes are located between nifH and nifD (Sibold et al 1991, Chien and Zinder 1994, Kessler et al 1998, Arcondeguy et al 2001. Phylogenetic analysis of the deduced amino acid sequence of the M. mazei Gö1 nif genes showed that they are most closely related to M. barkeri nif2 genes, suggesting that M. mazei Gö1 has a molybdenum-containing nitrogenase (Table 1).…”

“…Sequence analysis of this nif gene cluster was performed with the Genetics Computer Group (GCG) software package (Devereux et al 1984), and revealed five genes with sequence similarities to nitrogen fixation genes nifH, nifD, nifK, nifE and nifN. In addition, two genes located between nifH and nifD showed sequence similarities to bacterial glnB genes (Sibold et al 1991, Merrick and Edwards 1995, Arcondeguy et al 2001) and were, therefore, designated nifI 1 and nifI 2 , respectively. Additional open reading frames in the adjacent regions on either side of the cluster have been tentatively identified as a flavine-containing oxidoreductase (upstream of nifH) and a periplasmic molybdate binding protein plus a molybdenum transporter (downstream of nifN).…”

“…However, in contrast, (i) methanogenic nif gene promoters are typical archaeal promoters, and the transcriptional apparatus is similar to that of Eucarya (Langer and Zillig 1993, Marsh et al 1994, Langer et al 1995, Qureshi et al 1995, Hausner et al 1996, Thomm 2000, Bell and Jackson 2001, (ii) the archaeal nif genes are present in a single operon, and (iii) all diazotrophic methanogens contain two open reading frames (ORFs) inserted between nifH and nifD that show a strong similarity to glnB (Sibold et al 1991, Merrick and Edwards 1995, Arcondeguy et al 2001, Kessler et al 2001. Recently, this nif gene organization with the two glnB-like genes, which have been renamed nifI 1 and nifI 2 (Arcondeguy et al 2001), has also been found in Clostridium acetobutylicum (Nölling et al 2001) and Clostridium beijerinckii (Chen et al 2001). The presence of the nifI ORFs within the bacterial nif operon may be the result of a horizontal interdomain gene transfer, or this respective arrangement is ancestral and other bacteria have lost it.…”

Metabolic analysis of Chlorobium chlorochromatii CaD3 reveals clues of the symbiosis in ‘Chlorochromatium aggregatum’

“…chlorochromatii CaD3 like cyanobacteria lack GlnD homologs (Arcondéguy et al, 2001). However, differing from cyanobacteria that have only GlnB, Chl.…”

Inter-subunit interactions between Glutamate-Like Receptors inArabidopsis

“…4,5 Some mechanisms for amino acid sensing have been documented in bacteria, yeast, and mammals, and potential homologs of such amino acid sensors from other organisms do exist in plants. One example is Glb1, an Arabidopsis homolog of bacterial PII proteins that are considered N "master regulators," [6][7][8][9] although the role of Glb1 seems to be constrained compared with the bacterial counterparts. 10 Likewise, Arabidopsis homolog of Target of Rapamycin (TOR) plays a role in integrating nutrition signals including nitrogen in a similar manner as its yeast and animal counterparts.…”