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Clostridium clariflavum: Key Cellulosome Players Are Revealed by Proteomic Analysis.

Artzi L, Morag E, Barak Y, Lamed R, Bayer EA - MBio (2015)

Bottom Line: The results suggest that the expression of the cellulosome proteins is regulated by the type of substrate in the growth medium.Bioethanol produced from dedicated crops and cellulosic waste can provide a partial answer, yet a cost-effective production method must be developed.Identification of the major cellulosomal components expressed during growth of the bacterium and their influence on its catalytic capabilities provide insight into the performance of the remarkable cellulosome of this intriguing bacterium.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel.

No MeSH data available.


Related in: MedlinePlus

Major cellulosomes produced by C. clariflavum. Gel filtration separation of the spent growth medium resulted in two fractions which contain five major types of cellulosome complexes. (A) Two very large cellulosomes are present in fraction I. (i) Complex 1 is composed of five subunits of the octavalent ScaA, 40 enzymes, and the pentavalent ScaB. (ii) Complex II contains 7 subunits of ScaA, 56 enzymes, and the heptavalent ScaE. (B) Fraction II contains three cellulosomes. (i) Complex 1 contains a single ScaA subunit, 8 enzymes, and a monovalent ScaF. (ii) Complex 2 contains the hexavalent ScaM(b) subunit and 6 enzymes. (iii) Complex 3 contains ScaG, which binds a single enzyme via its type I cohesin module.
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fig3: Major cellulosomes produced by C. clariflavum. Gel filtration separation of the spent growth medium resulted in two fractions which contain five major types of cellulosome complexes. (A) Two very large cellulosomes are present in fraction I. (i) Complex 1 is composed of five subunits of the octavalent ScaA, 40 enzymes, and the pentavalent ScaB. (ii) Complex II contains 7 subunits of ScaA, 56 enzymes, and the heptavalent ScaE. (B) Fraction II contains three cellulosomes. (i) Complex 1 contains a single ScaA subunit, 8 enzymes, and a monovalent ScaF. (ii) Complex 2 contains the hexavalent ScaM(b) subunit and 6 enzymes. (iii) Complex 3 contains ScaG, which binds a single enzyme via its type I cohesin module.

Mentions: The separation of the cellulosome complexes from the spent growth medium by gel filtration resulted in an elution profile of two broad peaks, containing two discrete groups of cellulosome fractions. Mass spectrometry analysis showed that each peak contains cellulosomal proteins that differ in content and ratios of their component parts. The results allowed us to deduce the existence of several different types of cellulosome assemblies, shown in Fig. 3. The higher-molecular-mass first peak is mainly composed of two main complexes: (i) the ScaB adaptor scaffoldin, which carries five molecules of the primary scaffoldin ScaA, each of which bears eight enzymatic subunits, yielding a complex of 40 enzymatic subunits (assuming full occupancy), and (ii) the cell-free ScaE, which carries seven ScaA molecules, resulting in complexes containing up to 56 enzymes (Fig. 3A). Considering the abundance of ScaB and ScaE in fraction I, the ScaB-based complex is the most abundant. In contrast, the second peak includes a different set of complex compositions of lower molecular mass: (i) the monovalent cell wall ScaF interacts with a single ScaA molecule and its eight enzymes; (ii) ScaM(b), a scaffoldin bearing six type I cohesins, interacts with six type I dockerins conjugated to a variety of enzymes; and (iii) the single type I cohesin module of ScaG interacts with a type I dockerin of a cellulosomal enzyme (Fig. 3B). The variety of expressed cellulosomes discovered in this work reveal two complementary mechanisms of action employed by the bacterium in order to degrade the plant cell wall efficiently: cell-bound cellulosomes and cell-free cellulosomes, both cooperating to achieve effective deconstruction of plant cell wall polysaccharides. The lack of the anchoring scaffoldins ScaC and ScaD in the two fractions was surprising, since we would have expected to find them at levels that would fit the amounts of ScaA and ScaB according to the molar number of ScaC and ScaD cohesins versus that of the ScaA and ScaB dockerins. This may suggest that (unlike ScaF and ScaG) ScaC and ScaD remain bound to the cell wall by a particularly strong interaction and are not easily released to the medium.


Clostridium clariflavum: Key Cellulosome Players Are Revealed by Proteomic Analysis.

Artzi L, Morag E, Barak Y, Lamed R, Bayer EA - MBio (2015)

Major cellulosomes produced by C. clariflavum. Gel filtration separation of the spent growth medium resulted in two fractions which contain five major types of cellulosome complexes. (A) Two very large cellulosomes are present in fraction I. (i) Complex 1 is composed of five subunits of the octavalent ScaA, 40 enzymes, and the pentavalent ScaB. (ii) Complex II contains 7 subunits of ScaA, 56 enzymes, and the heptavalent ScaE. (B) Fraction II contains three cellulosomes. (i) Complex 1 contains a single ScaA subunit, 8 enzymes, and a monovalent ScaF. (ii) Complex 2 contains the hexavalent ScaM(b) subunit and 6 enzymes. (iii) Complex 3 contains ScaG, which binds a single enzyme via its type I cohesin module.
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Related In: Results  -  Collection

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Show All Figures
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fig3: Major cellulosomes produced by C. clariflavum. Gel filtration separation of the spent growth medium resulted in two fractions which contain five major types of cellulosome complexes. (A) Two very large cellulosomes are present in fraction I. (i) Complex 1 is composed of five subunits of the octavalent ScaA, 40 enzymes, and the pentavalent ScaB. (ii) Complex II contains 7 subunits of ScaA, 56 enzymes, and the heptavalent ScaE. (B) Fraction II contains three cellulosomes. (i) Complex 1 contains a single ScaA subunit, 8 enzymes, and a monovalent ScaF. (ii) Complex 2 contains the hexavalent ScaM(b) subunit and 6 enzymes. (iii) Complex 3 contains ScaG, which binds a single enzyme via its type I cohesin module.
Mentions: The separation of the cellulosome complexes from the spent growth medium by gel filtration resulted in an elution profile of two broad peaks, containing two discrete groups of cellulosome fractions. Mass spectrometry analysis showed that each peak contains cellulosomal proteins that differ in content and ratios of their component parts. The results allowed us to deduce the existence of several different types of cellulosome assemblies, shown in Fig. 3. The higher-molecular-mass first peak is mainly composed of two main complexes: (i) the ScaB adaptor scaffoldin, which carries five molecules of the primary scaffoldin ScaA, each of which bears eight enzymatic subunits, yielding a complex of 40 enzymatic subunits (assuming full occupancy), and (ii) the cell-free ScaE, which carries seven ScaA molecules, resulting in complexes containing up to 56 enzymes (Fig. 3A). Considering the abundance of ScaB and ScaE in fraction I, the ScaB-based complex is the most abundant. In contrast, the second peak includes a different set of complex compositions of lower molecular mass: (i) the monovalent cell wall ScaF interacts with a single ScaA molecule and its eight enzymes; (ii) ScaM(b), a scaffoldin bearing six type I cohesins, interacts with six type I dockerins conjugated to a variety of enzymes; and (iii) the single type I cohesin module of ScaG interacts with a type I dockerin of a cellulosomal enzyme (Fig. 3B). The variety of expressed cellulosomes discovered in this work reveal two complementary mechanisms of action employed by the bacterium in order to degrade the plant cell wall efficiently: cell-bound cellulosomes and cell-free cellulosomes, both cooperating to achieve effective deconstruction of plant cell wall polysaccharides. The lack of the anchoring scaffoldins ScaC and ScaD in the two fractions was surprising, since we would have expected to find them at levels that would fit the amounts of ScaA and ScaB according to the molar number of ScaC and ScaD cohesins versus that of the ScaA and ScaB dockerins. This may suggest that (unlike ScaF and ScaG) ScaC and ScaD remain bound to the cell wall by a particularly strong interaction and are not easily released to the medium.

Bottom Line: The results suggest that the expression of the cellulosome proteins is regulated by the type of substrate in the growth medium.Bioethanol produced from dedicated crops and cellulosic waste can provide a partial answer, yet a cost-effective production method must be developed.Identification of the major cellulosomal components expressed during growth of the bacterium and their influence on its catalytic capabilities provide insight into the performance of the remarkable cellulosome of this intriguing bacterium.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel.

No MeSH data available.


Related in: MedlinePlus