Classification of Moonlighting Proteins

In this section we examine the structural data that are available for moonlighting proteins and propose a classification of moonlighting proteins based on the spatial locations of the experimentally verified functional sites exploited by a protein to

Table 2.1 Proteins having distinct sites for different functions in the same domain.

Protein (organism)

Function 1

Function 2

Structure

Refs

Enolase

(S. pneumoniae)

Enolase (EC 4.2.1.11)

Binds plasminogen

1W6T

[31]

Albaflavenone

Albaflavenone

Terpene synthase

3EL3

[32, 33]

monooxygenase

(S. coelicolor A3(2))

monooxygenase (EC 1.14.13.106)

(EC 4.2.3.47)

MAPK1/ERK2 (H. sapiens)

Mitogen-activated protein kinase 1 (EC 2.7.11.24)

Transcriptional repressor (binds DNA)

4G6N

[34]

1-Cys Peroxiredoxin (H. sapiens)

Phospholipase A2 (EC 3.1.1.4)

Glutathione peroxidase (EC 1.11.1.15)

1PRX

[35]

Cytochrome C (S. cerevisiae)

Electron carrier protein in electron transport chain

Promotes apoptosis (binds Apaf-1)

1YCC

[36]

GCN4 (S. cerevisiae)

Transcription factor (binds DNA)

Ribonuclease (EC 3.1.27.5)

1YSA

[37]

I-Anii (A. nidulans)

Homing endonuclease (EC 3.1.-.-)

Transcriptional repressor (binds DNA)

3EH8

[3, 38]

perform its primary and moonlighting function(s). The primary and moonlighting function(s) of the proteins are referred to as ‘Function 1' and ‘Function 2' in the following. The moonlighting proteins were taken from the database of moonlighting proteins, MoonProt [27], and recently published papers which had known structural information along with experimentally verified functional sites responsible for the primary and moonlighting function(s) of the protein. Information on catalytic site residues for the proteins was extracted from the Catalytic Site Atlas (CSA), and additional functional annotation was extracted from PDBsum [6] and SwissProt. The various categories are proteins: (1) having distinct sites for different functions in the same domain (Table 2.1 [31-38]); (2) having distinct sites for different functions in different domains (Table 2.2; [39-44]); (3) using the same residues for different functions (Table 2.3; [45-47]); (4) using different residues in the same/overlapping site for different functions (Table 2.4; [48-53]); and (5) using different structural conformations or folds for different functions (Table 2.5; [54-56]).

 
Source
< Prev   CONTENTS   Source   Next >