Wireless Sensor and Actuator Networks (WSANs) are emerging as a new generation of Wireless Sensor Networks (WSNs). Due to the coupling between the sensing areas of the sensors and the action areas of the actuators, the efficient coordination among the nodes is a great challenge. In this paper, we address the problem of distributed node coordination in WSANs aiming at meeting the user's requirements on the states of the Points of Interest (POIs) in a real-time and energy-efficient manner. The node coordination problem is formulated as a non-linear program. To solve it efficiently, the problem is divided into two correlated subproblems: the Sensor-Actuator (S-A) coordination and the Actuator-Actuator (A-A) coordination. In the S-A coordination, a distributed federated Kalman filter-based estimation approach is applied for the actuators to collaborate with their ambient sensors to estimate the states of the POIs. In the A-A coordination, a distributed Lagrange-based control method is designed for the actuators to optimally adjust their outputs, based on the estimated results from the S-A coordination. The convergence of the proposed method is proved rigorously. As the proposed node coordination scheme is distributed, we find the optimal solution while avoiding high computational complexity. The simulation results also show that the proposed distributed approach is an efficient and practically applicable method with reasonable complexity.