22 research outputs found
Genome-Based Analysis of Heme Biosynthesis and Uptake in Prokaryotic Systems
No full textHeme is the prosthetic group of many proteins that carry out a variety of key biological functions. In addition, for many pathogenic organisms, heme (acquired from the host) may constitute a very important source of iron. Organisms can meet their heme demands by taking it up from external sources, by producing the cofactor through a dedicated biosynthetic pathway, or both. Here we analyzed the distribution of proteins specifically involved in the processes of heme biosynthesis and heme uptake in 474 prokaryotic organisms. These data allowed us to identify which organisms are capable of performing none, one, or both processes, based on the similarity to known systems. Some specific instances where one or more proteins along the pathways had unusual modifications were singled out. For two key protein domains involved in heme uptake, we could build a series of structural models, which suggested possible alternative modes of heme binding. Future directions for experimental work are given
Genome-Based Analysis of Heme Biosynthesis and Uptake in Prokaryotic Systems
No full textHeme is the prosthetic group of many proteins that carry out a variety of key biological functions. In addition, for many pathogenic organisms, heme (acquired from the host) may constitute a very important source of iron. Organisms can meet their heme demands by taking it up from external sources, by producing the cofactor through a dedicated biosynthetic pathway, or both. Here we analyzed the distribution of proteins specifically involved in the processes of heme biosynthesis and heme uptake in 474 prokaryotic organisms. These data allowed us to identify which organisms are capable of performing none, one, or both processes, based on the similarity to known systems. Some specific instances where one or more proteins along the pathways had unusual modifications were singled out. For two key protein domains involved in heme uptake, we could build a series of structural models, which suggested possible alternative modes of heme binding. Future directions for experimental work are given
Genome-Based Analysis of Heme Biosynthesis and Uptake in Prokaryotic Systems
No full textHeme is the prosthetic group of many proteins that carry out a variety of key biological functions. In addition, for many pathogenic organisms, heme (acquired from the host) may constitute a very important source of iron. Organisms can meet their heme demands by taking it up from external sources, by producing the cofactor through a dedicated biosynthetic pathway, or both. Here we analyzed the distribution of proteins specifically involved in the processes of heme biosynthesis and heme uptake in 474 prokaryotic organisms. These data allowed us to identify which organisms are capable of performing none, one, or both processes, based on the similarity to known systems. Some specific instances where one or more proteins along the pathways had unusual modifications were singled out. For two key protein domains involved in heme uptake, we could build a series of structural models, which suggested possible alternative modes of heme binding. Future directions for experimental work are given
Genome-Based Analysis of Heme Biosynthesis and Uptake in Prokaryotic Systems
No full textHeme is the prosthetic group of many proteins that carry out a variety of key biological functions. In addition, for many pathogenic organisms, heme (acquired from the host) may constitute a very important source of iron. Organisms can meet their heme demands by taking it up from external sources, by producing the cofactor through a dedicated biosynthetic pathway, or both. Here we analyzed the distribution of proteins specifically involved in the processes of heme biosynthesis and heme uptake in 474 prokaryotic organisms. These data allowed us to identify which organisms are capable of performing none, one, or both processes, based on the similarity to known systems. Some specific instances where one or more proteins along the pathways had unusual modifications were singled out. For two key protein domains involved in heme uptake, we could build a series of structural models, which suggested possible alternative modes of heme binding. Future directions for experimental work are given
The Functions of Sco Proteins from Genome-Based Analysis
No full textSco proteins are widespread proteins found in eukaryotic as well as in many prokaryotic organisms.
The 3D structure of representatives from human, yeast, and Bacillus subtilis has been determined,
showing a thioredoxin-like fold. Sco proteins have been implicated mainly as copper transporters
involved in the assembly of the CuA cofactor in cytochrome c oxidase. Some mutations have been
identified in humans that lead to defective cytochrome c oxidase formation and thus to fatal illnesses.
However, it appears that the physiological function of Sco proteins goes beyond assembly of the CuA
cofactor. Extensive analysis of completely sequenced prokaryotic genomes reveals that 18% of them
contain either Sco proteins but not CuA-containing proteins or vice versa. In addition, in several cases,
multiple Sco-encoding genes occur even if only a single potential Sco target is encoded in the genome.
Genomic context analysis indeed points to a more general role for Sco proteins in copper transport,
also to copper enzymes lacking a CuA cofactor. To obtain further insight into the possible role of Sco
in the assembly of other cofactors, a search for Cox11 proteins, which are important for CuB biosynthesis,
was also performed. A general framework for the action of Sco proteins is proposed, based on the
hypothesis that they can couple metal transport and thiol/disulfide-based oxidoreductase activity, as
well as select between either of these two cellular functions. This model reconciles the variety of
experimental observations made on these proteins over the years, and can constitute a basis for further
studies.
Keywords: Sco • cytochrome c oxidase assembly • CuA • copper transport • redox protectio
