Protein is a flexible material with broad distribution of conformations forming an energy landscape of quasi-stationary states. Disentangling the system dynamics along this landscape is the key for understanding the functioning of the protein. Here we studied a photosynthetic antenna pigment-protein complex LH2 with single molecule two-dimensional polarization imaging. Modeling based on the Redfield relaxation theory well describes the observed polarization properties of LH2 fluorescence and fluorescence excitation, strongly suggesting that at 77 K the conformational subspace of the LH2 is limited to about three configurations with relatively frequent switching among each other. At room temperature the next level of fluctuations determines the conformational dynamics. The results support the multitier model of the energy landscape of proteins and demonstrate the potential of the method for the studies of structural dynamics in proteins.